Cardiovascular protective role of a low-dose antihypertensive combination in obese Zucker rats

OBJECTIVE: Obesity, non-insulin-dependent diabetes mellitus (NIDDM) and hypertension are leading causes associated with increased cardiovascular morbidity and mortality. In modern times, the combined first line antihypertensive therapy with at least two drugs with a different mechanism of action to achieve a better blood pressure control, is increasing in acceptance worldwide. The aim of the present study was to determine possible beneficial effects of the low-dose combination (LDC) of an angiotensin-converting enzyme (ACE) inhibitor, perindopril (PER), and the diuretic indapamide (IND), regarding myocardial and vessels protection in an animal model of hypertension, obesity and NIDDM, such as the obese Zucker rat (OZR), and control lean Zucker rats (LZR). DESIGN: Ten-week-old male OZR (fa/fa) and LZR (Fa/fa) were used in this study. OZR group (G1, n=8), OZR with LDC group (G2, n=8); LZR group (G3, n=8) and LZR with LDC group (G4, n=8). During 6 months, G2 and G4 received a daily dose of 1 mg/kg combination of 0.76 mg/kg PER + 0.24 mg/kg IND, (ratio of doses 0.32), by gavage, and G1 and G3 received an equal volume of vehicle throughout the experiment. In order to evaluate cardiac dimensions and left ventricular mass (LVM) transthoracic echocardiograms were performed, at baseline and at the end of the experiment. Urine and blood samples for biochemical determination were obtained. After 6 months of treatment all rats were sacrificed, hearts were harvested for light microscopy (LM), high-resolution light microscopy (HRLM), immunohistochemistry including monoclonal antibodies against transforming growth factor beta (TGFbeta1) and anti-collagen type I (COL I) and type III (COL III) and electron microscopy (EM) studies. RESULTS: At the end of the study OZR treated with LDC presented: (1) lower blood pressure (128.9 +/- 4 versus 150.3 +/- 3.6 mmHg, P< 0.05); (2) smaller cardiac dimensions (P< 0.01); (3) lower LVM/100 g body weight (0.17 +/- 0.02 versus 0.30 +/- 0.05, P< 0.01); (4) higher fractional shortening (34.5 +/- 3.2 versus 23.3 +/- 5.9%, P< 0.01) than OZR untreated. Moreover, OZR that received LDC showed higher: (1) myocyte density (48 +/- 1.5 versus 20 +/- 2.5 myocytes/area, P< 0.01); (2) capillary density (30.5 +/- 3.1 versus 9.5 +/- 1.6 capillaries/area, P<0.01); (3) myofilament thickness (12.05 +/- 0.27 versus 9.83 +/- 0.39 nm, P<0.01); and lower amounts of: (1) TGFbeta1 in myocytes (P< 0.01), interstitium (P< 0.01) and vessel wall (P< 0.05); (2) COL I and COL III (P< 0.01), and COL I /COL III ratio (P< 0.01), compared with untreated OZR. Finally, OZR-treated with LDC showed not only unsubstantial modification in carbohydrate and lipid metabolism when compared with untreated OZR, but also an improvement in insulin/glucose ratio (P< 0.05). CONCLUSION: These results suggest that LDC of PER + IND can control cardiovascular damage in OZR providing an additional help in the metabolic scenario likewise.     

Intestinal dopaminergic activity in obese and lean Zucker rats: response to high salt intake

The present study examined intestinal dopaminergic activity and its response to high salt (HS, 1% NaCl over a period of 24 hours) intake in obese (OZR) and lean Zucker rats (LZR). The basal Na+,K+-ATPase activity (nmol Pi/mg protein/min) in the jejunum of OZR was higher than in LZR on normal salt (NS) (OZR-NS = 111.3 +/- 6.0 vs. LZR-NS = 88.0 +/- 8.3). With the increase in salt intake, the basal Na+,K+-ATPase activity significantly increased in both animals (OZR-HS = 145.9 +/- 11.8; LZR-HS = 108.8 +/- 6.7). SKF 38393 (10 nM), a specific D1-like dopamine receptor agonist, inhibited the jejunal Na+,K+-ATPase activity in OZR on HS intake, but failed to inhibit enzyme activity in OZR on NS intake and LZR on NS and HS intakes. The aromatic L-amino acid decarboxylase (AADC) activity in OZR was lower than in LZR on NS intake. The HS intake increased AADC activity in OZR, but not in LZR. During the NS intake the jejunal monoamine oxidase (MAO) activity in OZR was similar to that in LZR. The HS intake significantly decreased MAO activity in both OZR and LZR. The jejunal COMT activity in OZR was higher than in LZR on NS intake. The HS intake reduced COMT activity in OZR but not LZR. It is concluded that inhibition of jejunal Na+,K+-ATPase activity through D1 dopamine receptors is dependent on salt intake in OZR, whereas in LZR, the enzyme failed to respond to the activation of D1 dopamine receptors irrespective of their salt intake.     

Preserved insulin vasorelaxation and up-regulation of the Akt/eNOS pathway in coronary arteries from insulin resistant obese Zucker rats

Obesity is associated with insulin resistance in the peripheral vasculature and is an important risk factor for coronary artery disease. The current study assessed whether the vascular effects and the signaling pathways of insulin are impaired in coronary arteries from a rat model of genetic obesity. Intramyocardial arteries from obese Zucker rats (OZR) and lean Zucker rats (LZR) were mounted in microvascular myographs to assess insulin vasoactive effects and the proteins of the insulin pathway were determined by Western blotting. The endothelium-dependent and nitric oxide (NO)-mediated vasorelaxant effect of insulin was similar in arteries from LZR and OZR and blunted by inhibition of phosphatidylinositol 3-kinase (PI3K) and endothelial NO synthase (eNOS), but unaltered by either mitogen activated protein kinase (MAPK) or endothelin (ET) receptor blockade. Basal levels of phospho-eNOS Ser(1177) and phospho-Akt Ser(473) were up-regulated in OZR, and insulin increased phosphorylation of eNOS and Akt in both LZR and OZR. Moreover, insulin enhanced Akt expression in LZR. Basal and insulin-stimulated levels of phospho-MAPK p42/p44 were lower in OZR and palmitic acid reduced these levels in LZR. Coronary arteries are protected from vascular IR. The results underscore the fact that preservation of insulin-mediated vasorelaxation along with an up-regulation of the Akt/eNOS pathway and an impairment of the MAPK cascade account for this protection.     

Proangiogenic effect of angiotensin-converting enzyme inhibition is mediated by the bradykinin B(2) receptor pathway

Recent studies have suggested a proangiogenic effect of angiotensin-converting enzyme (ACE) inhibition. We hypothesized that such a proangiogenic effect of ACE inhibition may be mediated, in part, by bradykinin (BK) B(2)-receptor pathway. This study therefore examined the neovascularization induced by ACE inhibitor treatment in B(2) receptor-deficient mice (B(2)(-/-)) in a model of surgically induced hindlimb ischemia. After artery femoral occlusion, wild-type and B(2)(-/-) mice were treated with or without ACE inhibitor (perindopril, 3 mg/kg/d) for 28 days. Angiogenesis was then quantitated by microangiography, capillary density measurement, and laser Doppler perfusion imaging. The protein levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) were determined by Western blot. In wild-type animals, vessel density and capillary number in the ischemic leg were raised by 1.8- and 1.4-fold, respectively, in mice treated with ACE inhibitor when compared with the nontreated animals (P<0.01). This corresponded to an improved ischemic/nonischemic leg perfusion ratio by 1.5-fold in ACE inhibitor-treated animals when compared with the untreated ones (0.87+/-0.07 versus 0.59+/-0.05, respectively, P<0.01). Activation of the angiogenic process was also associated with a 1.7-fold increase in tissue eNOS protein level in mice treated with ACE inhibitor (P<0.05 versus control) but not with changes in VEGF protein level. Conversely, ACE inhibition did not affect vessel density, blood flow, and eNOS protein level in ischemic hindlimb of B(2)(-/-) mice. Therefore, proangiogenic effect of ACE inhibition is mediated by B(2)-receptor signaling and was associated with upregulation of eNOS content, independently of VEGF expression.     

INTESTINAL DOPAMINERGIC ACTIVITY IN OBESE AND LEAN ZUCKER RATS: RESPONSE TO HIGH SALT INTAKE

The present study examined intestinal dopaminergic activity and its response to high salt (HS, 1% NaCl over a period of 24 hours) intake in obese (OZR) and lean Zucker rats (LZR). The basal Na⁺,K⁺-ATPase activity (nmol Pi/mg protein/min) in the jejunum of OZR was higher than in LZR on normal salt (NS) (OZR-NS=111.3±6.0 vs. LZR-NS=88.0±8.3). With the increase in salt intake, the basal Na⁺,K⁺-ATPase activity significantly increased in both animals (OZR-HS=145.9±11.8; LZR-HS=108.8±6.7). SKF 38393 (10?nM), a specific D₁-like dopamine receptor agonist, inhibited the jejunal Na⁺,K⁺-ATPase activity in OZR on HS intake, but failed to inhibit enzyme activity in OZR on NS intake and LZR on NS and HS intakes. The aromatic L-amino acid decarboxylase (AADC) activity in OZR was lower than in LZR on NS intake. The HS intake increased AADC activity in OZR, but not in LZR. During the NS intake the jejunal monoamine oxidase (MAO) activity in OZR was similar to that in LZR. The HS intake significantly decreased MAO activity in both OZR and LZR. The jejunal COMT activity in OZR was higher than in LZR on NS intake. The HS intake reduced COMT activity in OZR but not LZR. It is concluded that inhibition of jejunal Na⁺,K⁺-ATPase activity through D₁ dopamine receptors is dependent on salt intake in OZR, whereas in LZR, the enzyme failed to respond to the activation of D₁ dopamine receptors irrespective of their salt intake.     

Coronary microvasculature alteration in hypertensive rats. Effect of treatment with a diuretic and an ACE inhibitor

The development of hypertension is accompanied by rarefaction of arterioles and capillaries in both animal models and humans. Although many studies have examined the effects of antihypertensive therapies on hemodynamics, cardiac hypertrophy, and large vessel structure, the question of whether changes in microvascular density induced by hypertension can be restored by pharmacologic treatment has yet to be answered. We report a series of experiments performed in rats with renovascular hypertension induced by unilateral nephrectomy and renal artery stenosis (Goldblatt one-kidney, one-clip model). Animals were treated for 4 weeks, after renal artery clipping, either with an angiotensin converting enzyme inhibitor (perindopril [PER], 0.76 mg/kg/day), or with an indol derivative diuretic with specific vascular properties (indapamide [IDP], 0.24 mg/kg/day) or with the combination of both drugs at the same doses as during monotherapy. Coronary microvessel densities (arterioles and capillaries) were evaluated by double immunolabeling in nonserial cryostat sections of the left ventricular inner myocardium. After 4 weeks of hypertension (mean arterial pressure, 174+/-11 v 124+/-5 mm Hg in normotensive (NT) controls, P < .01), cardiac hypertrophy (+59%, P < .001) was associated with a significant increase in myocardial arteriolar density (+27%, P < .01), and a decrease in capillary density (-12%, P < .05). Treatment with PER prevented the increase in arterial pressure, heart weight, and arteriolar density, but did not significantly affect the low coronary capillary density in comparison with that measured in untreated hypertensive (HT) rats. Treatment with IDP preserved normal capillary myocardial density but did not significantly lower the blood pressure (BP) (169+/-9 mm Hg) and only slightly reduced the cardiac ventricular hypertrophy: - 14% v untreated HT (P < .05) and +37% v NT (P < .01). In the same way, IDP normalized the left ventricular capillary density in spontaneously HT rats (+18% v untreated rats, P < .01). The combination of both drugs, PER and IDP, at the same low doses as during monotherapy, resulted in normal levels of arterial pressure and complete normalization of cardiac hypertrophy and arteriolar and capillary myocardial densities. In conclusion, the results observed after PER suggest that blockade of the renin-angiotensin system could inhibit large coronary vessel growth but minimally affects the capillary density despite complete normalization of BP. Indapamide could have beneficial effect on myocardial capillary density. The combination of IDP and PER has additional effects and prevents the increase in BP and cardiac weight, and reverses microvascular rarefaction, specifically arteriolar and capillary densities.     

Twenty-four-hour ambulatory blood pressure monitoring efficacy of perindopril/indapamide first-line combination in hypertensive patients: the REASON study

BACKGROUND: Circadian blood pressure (BP) measurements provide more information on hypertensive complications than office BP measurements. The purpose of this study was to analyze the efficacy of the first-line combination of perindopril 2 mg plus indapamide 0.625 mg versus atenolol 50 mg on BP parameters and variability over 24 h in patients with hypertension. METHODS: A double-blind, randomized, controlled, 12-month study comparing perindopril/indapamide and atenolol was performed in 201 patients (age 55.0 years) with uncomplicated sustained essential hypertension. Ambulatory BP measurements (ABPM) were done every 15 min over 24 h. RESULTS: After 1 year of treatment, the decrease in systolic BP was significantly greater for perindopril/indapamide than for atenolol during the entire 24-h period (-13.8 v -9.2 mm Hg), the daytime and the nighttime periods (P <.01). Diastolic blood pressure (DBP) variations were comparable for the two groups (-7.2 v -8.3 mm Hg, NS). Pulse pressure (PP) reduction was also significantly greater for perindopril/indapamide than for atenolol (for the whole 24 h, -6.6 v -0.9 mm Hg, P <.001). The through to peak (T/P) BP ratio and the smoothness index were comparable in the two groups for DBP. For systolic blood pressure (SBP), higher values of the T/P ratio (0.80 v 0.59) and the smoothness index (1.45 v 0.98; P <.02) were achieved for the perindopril/indapamide combination than for atenolol. CONCLUSIONS: The perindopril/indapamide first-line combination decreased SBP and PP more effectively than atenolol. Moreover, the BP control effect was smooth and consistent throughout the 24-h dosing interval and BP reduction variability was lower than the one induced by atenolol.     

Restoration of coronary collateral growth in the Zucker obese rat:

The metabolic syndrome (MS), a condition characterized by several risk factors for coronary artery disease, including obesity, is associated with endothelial dysfunction and oxidative stress. Because proper endothelial function is essential for signaling of certain growth factors (vascular endothelial growth factor, VEGF) we hypothesized that coronary collateral growth (CCG) is impaired in a model of the MS. To test this hypothesis, we stimulated coronary collateral growth in pre-diabetic Zucker obese fatty rats (OZR) and lean littermates (LZR) by using episodic, repetitive ischemia (RI: 40 s left anterior descending arterial occlusion, 24/d for 14 d). Myocardial blood flow (MBF, radioactive microspheres) was measured in the normal (NZ) and collateral-dependent (ischemic) zones (CZ); CCG was assessed as a ratio of CZ/NZ flow (unity represents complete restoration of CZ flow). In LZR, CZ/NZ ratio increased from 0.18 ± 0.03 to 0.81 ± 0.07 after RI (P < 0.05). In contrast, in OZR rats CZ/NZ did not increase after RI (0.15 ± 0.04 vs 0.18 ± 0.04). To rectify abrogated collateral growth in OZR, we employed VEGF gene therapy (VEGF-transduced, strained-matched, cultured vascular smooth muscle cells [cVSMCs], delivered intracoronary). VEGF therapy modestly but not significantly increased the CZ/NZ ratio after RI (0.16 ± 0.05 vs 0.33 ± 0.06). To facilitate VEGF signaling,we reduced oxidative stress by transducing cVSMCs with both ecSOD and VEGF. This increased the CZ/NZ flow ratio after RI to 0.52 ± 0.04 (p < 0.05 vs. OZR [(0.19 ± 0.04]) indicating partial restoration of collateral growth. Our results demonstrate that coronary collateral growth is impaired in a model of the metabolic syndrome and that growth factor gene therapy with VEGF is made far more effective when it is coupled to an intervention that reduces oxidative stress. Supported by NIH grants HL32788 (WMC), HL65203 (WMC), HL73755 (WMC), and COBRE RR018766 (FP, PR,WMC), and American Heart Association Scientist Development Grant (PR), AHA Postdoctoral Fellowship Award (NH, PR).     

Antihypertensive and antihypertrophic effects of omapatrilat in SHR

Vasopeptidase inhibitors, such as omapatrilat are single molecules that simultaneously inhibit neutral endopeptidase (NEP) and angiotensin converting enzyme (ACE). In normotensive rats, a single dose of oral omapatrilat (10 mg/kg) and 1 mg/kg inhibited plasma ACE (P < .01) for 24 h and increased plasma renin activity for 8 h (P < .01). In vitro autoradiography using the specific NEP inhibitor radioligand 125I-RB104 and the specific ACE inhibitor radioligand 125I-MK351A showed omapatrilat (10 mg/kg) caused rapid and potent inhibition of renal NEP and ACE, respectively, for 24 h (P < .01). In spontaneously hypertensive rats, 10 days of oral omapatrilat (40 mg/kg/day) reduced blood pressure (vehicle 237 +/- 4 mm Hg; omapatrilat, 10 mg/kg, 212 +/- 4 mm Hg; omapatrilat 40 mg/kg, 197 +/- 4 mm Hg, P < .01) in a dose-dependent manner (10 v 40 mg/kg, P < .01). Left ventricular hypertrophy was significantly reduced by high-dose omapatrilat (vehicle 2.76 +/- 0.03 mg/g body weight; omapatrilat, 10 mg/kg, 2.71 +/- 0.02 mg/g; omapatrilat 40 mg/kg, 2.55 +/- 0.02 mg/g, P < .01) and omapatrilat also increased kidney weight compared to vehicle (both doses, P < .01). Omapatrilat caused significant inhibition of plasma ACE and increased plasma renin activity (both doses, P < .01), and in vitro autoradiographic studies indicated sustained inhibition of renal ACE and NEP (both doses, P < .01). Omapatrilat is a potent vasopeptidase inhibitor, and its antihypertensive effects are associated with inhibition of NEP and ACE at the tissue level and beneficial effects on cardiovascular structure. Relating the degree of tissue inhibition to physiologic responses may allow further definition of the role of local renin angiotensin and natriuretic peptide systems in the beneficial effects of vasopeptidase inhibitors.     

Effects of perindopril on aldosterone production in the failing human heart

The present study was designed to examine whether the production of aldosterone from the heart is suppressed by angiotensin-converting enzyme (ACE) inhibition in patients with heart failure. Forty-one patients with left ventricular systolic dysfunction were randomly divided into either the perindopril group (n = 21, perindopril 4 mg/day) or the placebo group (n = 20). Plasma levels of aldosterone and ACE activity were measured in the anterior interventricular vein, coronary sinus, and aortic root during cardiac catheterization. The levels of aldosterone as well as ACE activity were significantly higher at the anterior interventricular vein and the coronary sinus than at the aortic root in the placebo group (aldosterone: 92.1 +/- 9.0 vs 70.6 +/- 8.3 pg/ml [p <0.001]; 90.3 +/- 9.2 vs 70.6 +/- 8.3 pg/ml [p <0.001], respectively; ACE activity: 13.6 +/- 0.8 vs 12.2 +/- 0.7 IU/L [p <0.001], 13.4 +/- 0.8 vs 12.2 +/- 0.7 IU/L [p <0.001], respectively). On the other hand, there were no differences in the levels of aldosterone or ACE activity between the anterior interventricular vein and aortic root or between the coronary sinus and aortic root (aldosterone: 68.1 +/- 8.4 vs 69.9 +/- 9.4 pg/ml [p = NS]; 67.3 +/- 8.9 vs 69.9 +/- 9.4 pg/ml [p = NS], respectively; ACE activity: 9.7 +/- 0.8 vs 9.9 +/- 0.8 IU/L [p = NS]; 9.8 +/- 0.8 vs 9.9 +/- 0.8 IU/L, respectively) in the perindopril group. The levels of aldosterone as well as ACE activity were significantly lower at the anterior interventricular vein and coronary sinus in the perindopril group than in the placebo group. The difference in the level of aldosterone between the anterior interventricular vein and aortic root (Delta aldosterone [anterior interventricular vein - aortic root]) had a significant positive correlation with that of ACE activity (Delta ACE [anterior interventricular vein - aortic root]) (r = 0.536, p <0.001), whereas ACE activity in the aortic root had no significant correlation with either the aldosterone levels in the aortic root or Delta aldosterone (anterior interventricular vein - aortic root). Perindopril suppressed cardiac aldosterone production by mainly suppressing cardiac ACE activity in patients with heart failure. Thus, aldosterone production is activated in the failing ventricle and is suppressed by perindopril mainly via the suppression of cardiac ACE activity in patients with heart failure.     

Blunted glucose metabolism in anorexia nervosa

Only few studies have specifically investigated diet-induced thermogenesis in anorexia nervosa. Twenty women, 10 anorectics (body mass index [BMI] = 14.98 +/- 1.02 kg/m(2)) and 10 controls (BMI = 22.53 +/- 0.75 kg/m(2)) were studied. Body composition was evaluated by isotopic dilution. Respiratory gas exchange was measured by indirect calorimetry. An oral glucose load (75 g) was administered to the anorectics (A) and the controls (CA). The controls underwent a second load (CB) with a higher glucose amount (1.85 +/- 0.11 g/kg body weight [BW]) to compare with the load taken by anorectics. Glucose-induced thermogenesis (GIT) was computed for 300 minutes following the load as the percent increase of energy expenditure (EE) above resting-EE (REE). Serum glucose levels were lower in anorectic patients both in fasting (3.46 +/- 0.66 v 5.23 +/- 0.23 in CA, P <.01 v 5.32 +/- 0.34 mmol in CB, P <.01) and in the postprandial state (glucose area under the curve [AUC] 175.51 +/- 6.40 v 289.80 +/- 7.30 in CA, P <.01 v 324.65 mmol in CB, P <.001); insulin AUC was lower, 1,926 +/- 452 versus 41,148 +/- 2,071 in CA, P <.0001 versus 60,765.5 pmol in CB, P <.0001. REE, normalized by fat-free mass (FFM), was similar between groups. GIT was lower in anorectics (3.58 +/- 1.20 v 5.45 +/- 1.83 in CA, P <.05 v 9.09% +/- 1.05% in CB, P <.01). Glucose oxidation was higher in anorectics than in CA (689.44 +/- 72.22 v 333.32 +/- 32.98 micromol/L/min, P <.001), but similar to CB. Lipid oxidation become negative after 30 minutes in anorectics (postprandial lipid oxidation = -93.58 +/- 39.86 v 370.61 +/- 21.73 in CA, P <.0001 v 119.01 +/- 12.32 micromol/L/300 min in CB, P <.0001). Anorectic patients displayed a low REE and GIT. Carbohydrate oxidation was similar between groups; lipid oxidation was extremely reduced. An increased protein catabolism was observed.     

Impact of obesity on coronary microvascular function in the Zucker rat

OBJECTIVE: To test the hypothesis that vasomotor control is impaired in the coronary circulation of prediabetic obese (OZR) relative to lean Zucker rats (LZR). METHODS: Cardiac function was assessed with in vivo measures of cardiac output and microvascular structure and function was assessed in vitro using videomicroscopic techniques. RESULTS: OZR showed a marked hyperdynamic circulation with an increased cardiac output and elevated stroke volume. Contrary to the stated hypothesis, the authors found no diminution of vasodilator function and no augmentation of vasoconstriction. Indeed, dilation to acetylcholine was potentiated and vasoconstriction to endothelin was reduced in OZR compared to LZR. Structural characteristics of small coronary arteries were similar between LZR and OZR. CONCLUSIONS: Taken together, these results indicate that obesity, as manifested in the prediabetic OZR, does not impair coronary vasomotor control. This lack of dysfunction in the presence of the same risk factors that affect other beds may reflect a reversal of vascular injury by the increased metabolism and coronary blood flow caused by hyperdynamic cardiac function early in obesity.     

Angiotensin converting enzyme inhibition and arterial endothelial function in adults with Type 1 diabetes mellitus.

AIMS: Arterial endothelial dysfunction is a key early event in atherogenesis, and occurs in asymptomatic adults with Type 1 diabetes mellitus (DM). As angiotensin converting enzyme (ACE) inhibitors have been reported to reverse microvascular endothelial dysfunction acutely, we assessed the longer term effect of ACE inhibition on large vessel endothelial physiology in a randomized, crossover double-blind controlled clinical trial. METHODS: Flow-mediated arterial dilatation (FMD), which is largely due to endothelial release of nitric oxide, was assessed by vascular ultrasound in 20 Type 1 DM subjects with known endothelial dysfunction. These subjects, aged 28+/-5 years, were studied before and after 12 weeks oral therapy with either the ACE inhibitor perindopril 4 mg daily or the diuretic hydrene (triamterene 50 mg with hydrochlorothiazide 25 mg) daily. RESULTS: Although perindopril lowered both systolic and diastolic blood pressure by 2.7/3.2 mmHg, respectively (F3,78 = 4.7, P= 0.006; F3,78 = 3.2, P = 0.03), there was no significant effect of either perindopril or hydrene on FMD (baseline FMD before perindopril 4.6+/-2.5%, after 4.1+/-3.4%, baseline FMD before hydrene 5.4+/-3.6%, after 6.0+/-3.3%; F3,78= 1.9, P=0.1). Glycaemic control deteriorated slightly on hydrene whilst lipid levels, heart rate, resting blood flow and the arterial responses to nitroglycerine, a smooth muscle dilator, were unaffected by the treatment given. CONCLUSION: ACE inhibitor therapy for 3 months did not improve arterial endothelial function in Type 1 DM subjects.     

培哚普利在糖尿病大鼠肢体缺血后血管再生中的作用

目的探讨培哚普利在1型糖尿病（T1DM）大鼠肢体缺血后血管再生中的作用及相关机制。方法对T1DM大鼠模型予单侧肢体股动脉离断。分为对照（DM）组、培哚普利治疗（DMA）组和培哚普利＋内皮型一氧化氮合酶（eNOS）阻断剂治疗（DML）组。治疗4周后比较各组缺血肢体血管再生情况以及eNOS、血管内皮生长因子（VEGF）、碱性成纤维细胞生长因子（bFGF）的mRNA和蛋白表达水平。结果与正常对照（Nc）组相比,DM组的缺血肢体微血管密度（MVD）、eNOS、VEGF和bFGF的mRNA和蛋白表达均下降,DMA组上述指标明显上调（P均〈0．05）。DML组的MVD、eNOS和bFGF的mRNA和蛋白表达降低（P〈0．05）,而VEGF表达不受影响（P〉0．05）。结论T1DM大鼠的缺血性血管再生受损,与之有关的生长因子表达下调。培哚普利能促进T1DM大鼠缺血肢体的血管再生,其机制与eNOS、VEGF和bFGF的表达上调有关。     

Comparison of creatine ingestion and resistance training on energy expenditure and limb blood flow

This study determined the effects of 28 days of oral creatine ingestion (days 1 to 5 = 20g/d; [5 g 4 times daily]: days 6 to 28 = 10 g/d; [5 g twice daily]) alone and with resistance training (5 hours/week) on resting metabolic rate (RMR), body composition, muscular strength (1RM), and limb blood flow (LBF). Using a double-blind, placebo-controlled design, 30 healthy male volunteers (21 +/- 3 years; 18 to 30 years) were randomly assigned to 1 of 3 groups; pure creatine monohydrate alone (Cr; n = 10), creatine plus resistance training (Cr-RT; n = 10), or placebo plus resistance training (P-RT; n = 10). Body composition (DEXA, Lunar DPX-IQ), body mass, bench, and leg press 1RM (isotonic), RMR (indirect calorimetry; ventilated hood), and forearm and calf LBF (venous occlusive plethysmography) were obtained on all 30 subjects on 3 occasions beginning at approximately 6:00 AM following an overnight fast and 24 hours removed from the last training session; baseline (day 0), and 7 days and 29 days following the interventions. No differences existed among groups at baseline for any of the variables measured. Following the 28-day interventions, body mass (Cr, 73.9 +/- 11.5 v 75.6 +/- 12.5 kg; Cr-RT, 78.8 +/- 6.7 v 80.8 +/- 6.8 kg; P <.01) and total body water (Cr, 40.4 +/- 6.8 v 42.6 +/- 7.2 L, 5.5%; Cr-RT, 40.6 +/- 2.4 v 42.3 +/- 2.2 L, 4.3%; P <.01) increased significantly in Cr and Cr-RT, but remained unchanged in P-RT, whereas, fat-free mass (FFM) increased significantly in Cr-RT (63 +/- 2.8 v 64.7 +/- 3.6 kg; P <.01) and showed a tendency to increase in Cr (58.1 +/- 8.1 v 59 +/- 8.8 kg; P =.07). Following the 28-day period, all groups significantly increased (P <.01) bench (Cr, 77.3 +/- 4 v 83.2 +/- 3.6 kg; Cr-RT, 76.8 +/- 4.5 v 90.5 +/- 4.5 kg; P-RT, 76.0 +/- 3.4 v 85.5 +/- 3.2 kg), and leg press (Cr, 205.5 +/- 14.5 v 238.6 +/- 13.2 kg; Cr-RT, 167.7 +/- 13.2 v 238.6 +/- 17.3 kg; P-RT, 200.5 +/- 9.5 v 255 +/- 13.2 kg) 1RM muscular strength. However, Cr-RT improved significantly more (P <.05) on the leg press 1RM than Cr and P-RT and the bench press 1RM than Cr (P <.01). Calf (30%) and forearm (38%) LBF increased significantly (P <.05) in the Cr-RT, but remained unchanged in the Cr and P-RT groups following the supplementation period. RMR expressed on an absolute basis was increased in the Cr (1,860.1 +/- 164.9 v 1,907 +/- 173.4 kcal/d, 2.5%; P <.05) and Cr-RT (1,971.4 +/- 171.8 v 2,085.7 +/- 183.6 kcal/d, 5%; P <.05), but remained unchanged from baseline in P-RT. Total cholesterol decreased significantly in Cr-RT (-9.9%; 172 +/- 27 v 155 +/- 26 mg/dL; P <.01) compared with Cr (174 +/- 46 v 178 +/- 43 mg/dL) and P-RT (162 +/- 32 v 161 +/- 36 mg/dL) following the 28-day intervention. These findings suggest that the addition of creatine supplementation to resistance training significantly increases total and fat-free body mass, muscular strength, peripheral blood flow, and resting energy expenditure and improves blood cholesterol.     

Bone marrow molecular alterations after myocardial infarction: Impact on endothelial progenitor cells

OBJECTIVE: Standard drugs post-myocardial infarction (MI) such as angiotensin converting enzyme (ACE) and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) increase levels of endothelial progenitor cells (EPC). However, potential underlying mechanisms have not yet been investigated. METHODS AND RESULTS: We studied the effects of ACE inhibition or statin treatment on EPC levels and on bone marrow molecular pathways involved in EPC mobilization after MI in rats. Three days post-infarction, acetylated LDL (acLDL)+/Ulex europeus-1 (UEA-1)+/VEGF receptor-2+/eNOS+ EPC levels and formation of endothelial colony forming units (CFU) were reduced to 60+/-12% (p < 0.05) and 68+/-7% (p < 0.05). In bone marrow, extracellular signal-regulated kinase (ERK) phosphorylation and matrix metalloproteinase (MMP)-9 activity were repressed. Endothelial nitric oxide synthase (eNOS) activity was unchanged, whereas reactive oxygen species (ROS) were increased two-fold in bone marrow. ACE or HMG-CoA reductase inhibition resulted in significant increases in EPC levels. ACE inhibition increased bone marrow ERK phosphorylation and MMP-9 activity. Statin therapy enhanced bone marrow VEGF protein levels, Akt phosphorylation, eNOS activity and normalized increased ROS levels. Augmented EPC levels in the early post-infarction phase by ACE inhibition or statin treatment were associated with improved cardiac function and increased capillary density in the peri-infarct area 7 days after MI. Moreover, increased EPC levels in response to ACE inhibition or statin treatment were sustained 10 weeks post-infarction. CONCLUSIONS: Increased ROS and impaired MMP-9 activity in bone marrow likely contribute to reduced EPC mobilization in the early post-infarction phase. ACE inhibition or statin treatment increased EPC levels with distinct drug-specific effects on bone marrow molecular alterations.     

Hypertension-independent microvascular rarefaction in the obese Zucker rat model of the metabolic syndrome

OBJECTIVE: To test the hypothesis that reduced skeletal muscle microvessel density (MVD) in obese Zucker rats (OZR) is independent of chronic elevations in mean arterial pressure (MAP). METHODS: Microvessels in cross sections of gastrocnemius muscle from lean Zucker rats (LZR) and OZR were labeled with Griffonia simplicifolia I lectin, visualized with fluorescence microscopy and vessel number within sections was determined using imaging software. Rats were used at different ages to assess correlations between the temporal development of hypertension and microvascular rarefaction. Additionally, rats were chronically treated with captopril or hydralazine as antihypertensive therapies to examine the development of microvascular rarefaction in the absence of elevated blood pressure. RESULTS: MVD in muscle of OZR was reduced by approximately 17% versus LZR by 10-11 weeks of age, prior to any elevation in MAP. By 15-17 weeks, OZR exhibited a approximately 23% reduction in MVD and a approximately 25 mmHg increase in MAP. Treatment with hydralazine prevented elevated MAP in OZR, although this was not associated with an improved MVD. Captopril treatment also prevented elevated MAP in OZR, although a partial recovery of MVD toward normal levels was observed. This observation was associated with an improved insulin resistance. CONCLUSIONS: These results suggest that microvessel rarefaction in skeletal muscle of OZR manifesting the metabolic syndrome does not depend on an elevated mean arterial pressure and that other factors associated with the metabolic syndrome, possibly insulin resistance, may underlie the progressive reduction in MVD in these animals.     

Associations between nondipping of nocturnal blood pressure decrease and cardiovascular target organ damage in strictly selected community-dwelling normotensives

BACKGROUND: In hypertensives, nondippers are more likely than dippers to suffer silent, as well as overt, hypertensive target organ damage. In this study, we investigated whether a nondipper status was associated with target organ damage in normotensives. METHODS: We performed ambulatory blood pressure (BP) monitoring, echocardiography, and carotid ultrasonography and measured natriuretic peptides and urinary albumin (UAE) in 74 normotensive subjects with the following criteria: 1) clinical BP <140/90 mm Hg; 2) average 24-h ambulatory BP <125/80 mm Hg. RESULTS: The left ventricular mass index (LVMI) and the relative wall thickness (RWT) measured by echocardiography were greater in nondippers than dippers (LVMI: 103 +/- 26 v 118 +/- 34 g/m(2), P <.05; RWT: 0.38 +/- 0.07 v 0.43 +/- 0.09, P <.01). Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were higher in nondippers than dippers (ANP: 14 +/- 10 v 36 +/- 63 pg/mL, P <.01; BNP: 16 +/- 12 v 62 +/- 153 pg/mL, P <.05). There were no significant differences in UAE and intima-media thickness measured by carotid ultrasonography. CONCLUSIONS: Normotensive nondipping may not reflect renal damage, but may have a predominant effect on cardiac damage. Nondipping of nocturnal BP seems to be a determinant of cardiac hypertrophy and remodeling, and may result in a cardiovascular risk independent of ambulatory BP levels in normotensives.     

Diminished natriuretic response to dopamine D1 receptor agonist, SKF-38393 in obese Zucker rats

Dopamine causes natriuresis and diuresis via activation of D1 receptors located on the renal proximal tubules and subsequent inhibition of the sodium transporters, Na-H exchanger and Na+/K+ ATPase. We have reported that dopamine fails to inhibit the activities of these two transporters in the obese Zucker rats (OZR). The present study was designed to examine the functional consequence of this phenomenon by determining the natriuretic and diuretic response to D1 receptor activation in lean Zucker rats (LZR) and OZR. In 11-12 week-old OZR and LZR, natriuretic and diuretic responses to intravenously administered D1 receptor agonist, SKF 38393 (3 microg/kg/min for 30 min) were measured under Inactin anesthesia. Plasma insulin and glucose levels were significantly higher in the obese rats as compared to the lean rats. Intravenous infusion of SKF 38393 caused significant increases in urine flow, urinary sodium excretion (U(Na)V), fractional excretion of sodium (FE(Na)), and glomerular filtration rate (GFR) in the lean rats. However, the natriuretic and diuretic response to SKF 38393 was markedly blunted in OZR. Infusion of SKF 38393 did not cause significant changes in the mean blood pressure and heart rate in either of the two groups. We suggest that the diminished natriuretic response to D1 receptor activation in OZR is the consequence of the previously reported defect in the D1 receptor-G-protein coupling and the failure of dopamine to inhibit the sodium transporters in these animals.