The effect of chrysin‐loaded nanofiber on wound healing process in male rat

Wound healing is an inflammatory process. Chrysin, a natural flavonoid found in honey, has been recently investigated to have anti‐inflammatory and antioxidant effects. In this work, the effects of chrysin‐loaded nanofiber on the expressions of genes that are related to wound healing process such as P53, TIMPs, MMPs, iNOS, and IL‐6 in an animal model study were evaluated. The electrospinning method was used for preparation the different concentrations of chrysin‐loaded PCL‐PEG nanofiber (5%, 10%, and 20% [w/w]) and characterized by FTIR and SEM. The wound healing effects of chrysin‐loaded PCL‐PEG nanofiber were in vivo investigated in rats, and the expressions of genes related to wound healing process were evaluated by real‐time PCR. The study results showed chrysin‐loaded PLC‐PEG compared to chrysin ointment and control groups significantly increase IL‐6, MMP‐2, MMP‐8, MMP‐9, TIMP‐1, and TIMP‐2 (p < .05). On the other hand, nanofibers containing chrysin significantly decreased p53 and iNOS expression compared to chrysin ointment and control groups (p < .05). According to the results, chrysin‐loaded PCL‐PEG‐PCL nanofibers have positive effects on the expression of the genes that have pivotal role in wound healing.     

Prorenin receptor mediates inflammation in renal ischemia

We hypothesized that PRR contributes to renal inflammation in the 2‐kidney, 1‐clip (2K1C) renal ischaemia model. Male Sprague‐Dawley rats were fed normal sodium diet. Blood pressure (BP) was obtained on days 0 and 28 after left renal artery clipping that reduced renal blood flow by 40%. Renal expression of TNF‐α, COX‐2, NF‐κB, IL‐1β, MCP‐1 and collagen type I were assessed in sham and 2K1C rats with or without left renal administration of scramble or PRR shRNA. At baseline, there were no differences in BP. Compared to sham, MAP significantly increased in clipped animals (sham 102 ± 1.9 vs 2K1C 131.8 ± 3.09 mmHg, P < .05) and was not influenced by scramble or PRR shRNA treatment. Compared to sham and contra lateral (non‐clipped) kidney, there was upregulation in mRNA and protein expression of PRR (99% and 45%, P < .01), TNF‐α (72% and 50%, P < .05), COX‐2 (72% and 39%, P < .05), p‐NF‐κB (92%, P < .05), MCP‐1 (87%, P < .05) and immunostaining of collagen type I in the clipped kidney. These increases were not influenced by scramble shRNA. Compared to 2K1C and scramble shRNA, PRR shRNA treatment in the clipped kidney significantly reduced the expression of PRR (62% and 57%, P < .01), TNF‐α (51% and 50%, P < .05), COX‐2 (50% and 56%, P < .05), p‐NF‐κB by 68% (P < .05), MCP‐1 by 73% (P < .05) and collagen type I respectively. Ang II was increased in both kidneys and did not change in response to scramble or PRR shRNA treatments. We conclude that PRR mediates renal inflammation in renal ischaemia independent of blood pressure and Ang II.     

Acute hypotensive effect of diminazene aceturate in spontaneously hypertensive rats: role of NO and Mas receptor

Diminazene aceturate (DIZE) has been described as an angiotensin-converting enzyme 2 (ACE2) activator. We aimed to investigate DIZE effects on blood pressure (BP) of spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats. BP was recorded in awake and unrestrained rats 24 hours after femoral artery catheterization. DIZE (15 mg/kg, s.c.) produced a fast BP decrease only in SHR (P < .01). Pre-treatment with L-NAME (10 mg/kg, iv) did not change the hypotensive effect on systolic BP whereas mitigated the DIZE effect on diastolic BP (∆ Emax: −31 ± 5 DIZE vs −15 ± 1 mm Hg DIZE + L-NAME, P < .05). BP changes after DIZE remained unchanged after the treatment of rats with A-779 (50 ug/kg, iv), a Mas receptor blocker. Vasodilatation curves to DIZE (10^-9 to 10^-4 mol/L) in mesenteric arteries confirmed the NO-mediation on DIZE effects in SHR, as L-NAME (300 μmol/L) reduced the vascular sensitivity (∆EC50: −5.12 ± 0.09 CONTROL vs −4.66 ± 0.08 L-NAME, P < .05) and the magnitude of DIZE effect (area under the curve (AUC), 357.5 ± 8.2 DIZE vs 424.7 ± 11.6 L-NAME; P < .001), whereas A-779 (1 μmol/L) enhanced DIZE response (AUC, 357.5 ± 8.2 DIZE vs 309.8 ± 14.7 A-779, P < .05). Our findings indicate that DIZE acutely reduces the BP in SHR possibly by a mechanism other than Mas receptor activation. This effect seems to be mediated, at least partially, by NO.     

Pubertal administration of antiserum against nerve growth factor regresses renal vascular remodeling in spontaneously hypertensive rats

To investigate the role of nerve growth factor (NGF) in the development of hypertensive renal vascular remodeling, antiserum against NGF (anti‐NGF) or vehicle was injected at 3 weeks of age in spontaneously hypertensive rats (SHR) and Wistar–Kyoto (WKY) rats (n = 9 for each treatment in each strain). Flow‐pressure (F‐P) and pressure‐glomerular filtration rate (P‐GFR) relationships at vasodilated perfused kidneys were determined at 10 weeks of age. In the vehicle rats, blood pressure, renal noradrenaline content, the gradient of F‐P (minimal vascular resistance at pre‐ and post‐glomerular vasculature) and the X‐intercept of P‐GFR (preglomerular : postglomerular vascular resistance ratio) were greater in SHR than in WKY rats, although the gradient of P‐GFR (glomerular filtration capacity) did not differ significantly between the strains. Blood pressure and renal noradrenaline content were lower in SHR receiving anti‐NGF than in SHR receiving vehicle, although such difference was not observed in WKY rats. The gradient of F‐P was less but the gradient of P‐GFR was greater in SHR receiving anti‐NGF compared with SHR receiving vehicle, although the similar differences did not occur in WKY rats. Blood pressure and renal noradrenaline content remained greater in SHR treated with anti‐NGF compared with WKY rats treated with vehicle; however, the gradient of F‐P did not differ significantly between them. Contrary, anti‐NGF did not affect the X‐intercept of P‐GFR in either strain. In conclusion, NGF could contribute to the genesis of renal vascular remodeling, at least in part, through modification of renal sympathetic activity and blood pressure in SHR.     

Asiatic acid alleviates cardiovascular remodelling in rats with L‐NAME‐induced hypertension

A previous study demonstrated the antihypertensive effect of asiatic acid. The current study investigates the effect of asiatic acid on cardiovascular remodelling and possible mechanisms involved in N_ω‐nitro‐L‐arginine methyl ester hydrochloride (L‐NAME)‐induced hypertensive rats. Male Sprague–Dawley rats were treated with L‐NAME (40 mg/kg per day) for 3 weeks in order to induce hypertension. Hypertensive rats were administered asiatic acid (20 mg/kg per day) or vehicle for a further 2 weeks. It was found that hypertensive rats showed high systolic blood pressure, left ventricular (LV) hypertrophy, increases in LV fibrosis, aortic wall thickness and aortic collagen deposition (P < 0.05). Moreover, decreased plasma nitrate and nitrite (NOx) and increased plasma tumor necrosis factor alpha (TNF‐α) were observed in hypertensive rats (P < 0.05). This was consistent with downregulation of endothelial nitric oxide synthase (eNOS) expression and upregulation of inducible nitric oxide synthase (iNOS) expression in heart and aortic tissues (P < 0.05). Levels of malondialdehyde (MDA) in plasma, aortic and heart tissues were significantly increased in hypertensive rats (P < 0.05). Asiatic acid markedly reduced blood pressure, alleviated cardiovascular remodelling, and restored plasma NOx and TNF‐α as well as eNOS/iNOS expression in heart and aortic tissues (P < 0.05). Additionally, there was a significant reduction of MDA levels in the tissues of treated hypertensive rats. In conclusion, this study demonstrates the therapeutic effects of asiatic acid on blood pressure and cardiovascular remodelling, which is possibly related to the restoration of eNOS/iNOS expression, and the resulting anti‐inflammatory and antioxidant activities.     

血脂康对自发性高血压大鼠心肌重构的作用及其可能机制

目的观察血脂康(Xuezhikang,XZK)对自发性高血压大鼠(spontaneously hypertensive rats,SHR)左室肥厚和心肌间质纤维化的影响,探究其可能机制。方法 30只SHR,♂,随机分为3组,血脂康(300 mg.kg 1.d 1)治疗组(XZK组,n=10),辛伐他汀(5 mg.kg 1.d 1)治疗组(SIM组,n=10),SHR对照组(SHR组,n=10),同时入组同龄Wistar-Kyoto大鼠为正常对照组(WKY组,n=10),均予等容量0.9%生理盐水灌胃。12周后,分离心脏,左室称重并计算左室重量指数(LVWI),心肌组织固定包埋后Masson染色并计算心肌胶原容积分数(CVF)及心肌血管周围胶原面积(PVCA),测定血清Ⅰ型前胶原羧基末端前肽(PⅠCP)浓度、心肌组织超氧歧化酶(SOD)活性及丙二醛(MDA)浓度。结果与SHR组相比,XZK组和SIM组可以显著降低LVWI(P<0.05)、CVF(P<0.01)、PVCA(P<0.01)及血清PⅠCP浓度(P<0.01),但SOD活力及MDA浓度差异无统计学意义。结论血脂康能够显著减轻SHR的左室肥厚,降低心肌间质纤维化程度,并与血压和胆固醇水平的变化无关,血脂康表现出与辛伐他汀相同的抗心肌重构作用,作用机制可能与心肌SOD活性和MDA浓度相关不大。     

GCIP-27对自发性高血压大鼠左心室结构影响的实验研究

目的观察GCIP-27连续给药对自发性高血压大鼠(SHR)左心室结构的影响。方法30只SHR随机分为5组。空白溶剂对照组、阳性对照氯沙坦组(6mg·kg-1)和GCIP-27(10、30、90μg·kg-1ip,bid)3组,另6只Wistar-Kyoto大鼠(WKY)作为正常对照组。药物干预8wk后,测定SHR收缩压(SBP)、心室重量指数,分别用光镜、透射电镜观察心肌结构;VG染色测定心肌间质胶原含量。结果用药后第2周开始,SHR各剂量组(GCIP-2710、30、90μg·kg-1)SBP明显低于空白对照组(P<0·05);心肌重量指数(HMI)和左心室肥厚指数(LVMI)均明显降低(P<0·05);心肌间质胶原面积(CA)、胶原含量(IOD)及胶原容积分数(CVF)均明显减少(P<0·01)。光镜及电镜显示GCIP-27能明显改善SHR的心肌病理改变及超微结构。结论GCIP-27能明显改善SHR的心脏结构,降低心肌间质胶原增生,同时发挥降血压作用,进而对SHR左室重构的形成发挥干预及保护作用。     

硫化氢对自发性高血压大鼠胸主动脉舒张反应的影响

目的 探讨内源性及外源性硫化氢(H_2S)对自发性高血压大鼠(SHR)离体胸主动脉舒张反应的影响。方法 4wb WKY大鼠24只,随机分为WKY对照组(n=8)、WKY+H_2S组(n=8)及WKY+PPG组(n=8)。同样周龄SHR大鼠24只,随机分为高血压对照组(n=8)、高血压+H_2S组(n=8)及高血压+PPG组(n=8),高血压对照组及WKY对照组大鼠每日腹腔注射生理盐水,WKY+H_2S组及高血压+H_2S组每日腹腔注射硫氢化钠(NaHS),WKY+PPG组及高血压+PPG组每日腹腔注射PPG,5 wk后处死,取胸主动脉,观察其对乙酰胆碱(ACh)、硝普钠(SNP)及NaHS的舒张反应。结果 WKY+PPG组及高血压对照组、高血压+PPG组对ACh及SNP的舒张率较WKY组降低(P<0.05),而高血压+H_2S组较高血压对照组升高(P<0.05),与WKY对照组相似;各组大鼠血管环对SNP的舒 张反应均高于ACh(P<0.05);WKY对照组及高血压对照组对不同浓度的NaHS呈现剂量依赖性舒张反应,对于同样浓度的NaHS,高血压对照组较WKY对照组的舒张率高。结论 H_2S可以独立及与一氧化氮协同发挥舒张血管效应,在自发性高血压血管舒张功能异常的形成机制中占据重要地位。     

ANGIOTENSIN CONVERTING ENZYME INHIBITOR, CAPTOPRIL, INHIBITS CARDIAC HYPERTROPHY WITHOUT CHANGING COLLAGEN TYPES AND CONCENTRATION IN SPONTANEOUSLY HYPERTENSIVE RATS

1. The effects of the ACE inhibitor, captopril, on collagen metabolism in spontaneously hypertensive rats (SHR) with cardiac hypertrophy was examined. Captopril (100 mg/kg per day) was administered in drinking water to 20 week old male SHR for 12 weeks. Collagen concentration was calculated from hydroxyproline content, and relative proportions of types I, III and V collagen were determined by non-interrupted SDS-polyacrylamide gel electrophoresis (SDS-PAGE). These parameters were examined in age and sex matched Wistar-Kyoto (WKY) rats, as well as in non-treated SHR, and compared with those of captopril-treated SHR. 2. Captopril significantly reduced both blood pressure (191 ± 12.1 vs 146 ± 11.2 mmHg, P < 0.01), and the ratio of left ventricular (LV) weight to bodyweight (BW; 2.38 ± 0.17 vs 2.05 ± 0.12 mg/g, P < 0.01). There were no significant differences in collagen concentration among WKY rats, captopril-treated SHR and non-treated 32 week old SHR. However, total collagen content in captopril-treated SHR reduced significantly compared with non-treated 32 week old SHR (16.8 ± 2.0 vs 21.3 ± 0.8 mg, P < 0.01). The relative proportion of type V collagen was significantly higher in both captopril-treated (58.6 ± 3.4 vs 46.8 ± 1.3%, P < 0.01) and non-treated 32 week old SHR (59.9 ± 3.1 vs 46.8 ± 1.3%, P < 0.01) compared with WKY rats. However, there were no significant differences between captopril-treated SHR and non-treated 32 week old SHR. 3. The data from this study showed that captopril reduced cardiac hypertrophy, as reported previously, but did not change collagen types and concentration of the hypertrophied myocardium in SHR.     

Captopril avoids hypertension,the increase in plasma angiotensin II but increases angiotensin 1–7 and angiotensin II‐induced perfusion pressure in isolated kidney in SHR

相似文献   

Atorvastatin attenuates vascular remodelling in spontaneously hypertensive rats via the protein kinase D/extracellular signal-regulated kinase 5 pathway

The present study was conducted to determine whether atorvastatin reduces hypertension-induced vascular remodelling and whether its effects involve protein kinase D (PKD) and extracellular signal-regulated kinase 5 (ERK5). We used 16-week-old spontaneously hypertensive rats (SHRs) and age-matched Wistar-Kyoto (WKY) rats. The blood pressure and serum lipid concentration were measured. Changes in the vascular morphology and histology were examined using H&E, Masson^’s trichrome, and Sirius Red staining. The media thickness (MT), ratio of MT to lumen diameter (LD) (MT/LD), collagen volume fraction (CVF) and hydroxyproline content were measured to evaluate vascular remodelling. Atorvastatin (50 mg/kg/day) was administered for 8 weeks. Increased blood pressure and vascular remodelling were more prominent in SHRs than in WKY rats. SHRs also had elevated PKD and ERK5 activation. The systolic blood pressure, MT/LD ratio, and hydroxyproline content were positively correlated with the activation level of PKD and ERK5 in SHRs. Atorvastatin significantly attenuated the activation of PKD and ERK5. Overall, this study demonstrated that atorvastatin could reverse vascular remodelling in SHRs. The PKD/ERK5 signalling pathway might be important for elucidating the beneficial pleiotropic effects of atorvastatin on vascular remodelling.     

Strontium fructose 1,6‐diphosphate alleviates early diabetic testopathy by suppressing abnormal testicular matrix metalloproteinase system in streptozocin‐treated rats

Objectives Male hypogonadism is frequently associated with testopathy in patients with type 2 diabetes and in middle‐aged males. We hypothesized that abnormal matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in testis have large roles to play in male hypogonadism. It has been found in diabetic rats that a novel compound, strontium fructose 1,6‐diphosphate (FDP‐Sr), with extra high energy supply, could reverse male hypogonadism by normalizing MMP‐9 and TIMPs in the testis. We investigated whether FDP‐Sr could be promising in treating diabetic testopathy. Methods Adult male Sprague‐Dawley rats were administered a single dose of streptozocin (65 mg/kg, i.p.) to induce diabetes. The diabetic rats were treated with FDP‐Sr in three doses or testosterone propionate in the final four weeks during the eight‐week study. Key findings Serum testosterone, activity of marker enzymes, and mRNA of MMPs and TIMPs and protein of MMP‐9 in the testis were detected. After eight weeks, the activity of acid phosphatase, lactate dehydrogenase, succinate dehydrogenase and γ‐glutamyl transpeptidase in testis were significantly decreased (P < 0.01), accompanied by down‐regulated mRNA and activity of MMP‐2 and MMP‐9 (P < 0.01) and upregulated mRNA of TIMP‐1 and TIMP‐2. Downregulated MMP‐9 protein and degenerative changes in histology were predominant in diabetic testis. Conclusions FDP‐Sr or testosterone propionate significantly normalized expression and activity of the MMPs–TIMPs system to attenuate changes in serum testosterone, marker enzymes and histology in testis. Effects of FDP‐S‐r were dose‐dependent and comparable with those of testosterone propionate. By supplying extra energy, FDP‐Sr could be promising in treating diabetic testopathy by normalizing abnormal MMP‐9 and its endogenous inhibitors in testes.     

Differential cardiotoxicity in response to chronic doxorubicin treatment in male spontaneous hypertension-heart failure (SHHF), spontaneously hypertensive (SHR), and Wistar Kyoto (WKY) rats

Life threatening complications from chemotherapy occur frequently in cancer survivors, however little is known about genetic risk factors. We treated male normotensive rats (WKY) and strains with hypertension (SHR) and hypertension with cardiomyopathy (SHHF) with 8 weekly doses of doxorubicin (DOX) followed by 12 weeks of observation to test the hypothesis that genetic cardiovascular disease would worsen delayed cardiotoxicity. Compared with WKY, SHR demonstrated weight loss, decreased systolic blood pressure, increased kidney weights, greater cardiac and renal histopathologic lesions and greater mortality. SHHF showed growth restriction, increased kidney weights and renal histopathology but no effect on systolic blood pressure or mortality. SHHF had less severe cardiac lesions than SHR. We evaluated cardiac soluble epoxide hydrolase (sEH) content and arachidonic acid metabolites after acute DOX exposure as potential mediators of genetic risk. Before DOX, SHHF and SHR had significantly greater cardiac sEH and decreased epoxyeicosatrienoic acid (EET) (4 of 4 isomers in SHHF and 2 of 4 isomers in SHR) than WKY. After DOX, sEH was unchanged in all strains, but SHHF and SHR rats increased EETs to a level similar to WKY. Leukotriene D4 increased after treatment in SHR. Genetic predisposition to heart failure superimposed on genetic hypertension failed to generate greater toxicity compared with hypertension alone. The relative resistance of DOX-treated SHHF males to the cardiotoxic effects of DOX in the delayed phase despite progression of genetic disease was unexpected and a key finding. Strain differences in arachidonic acid metabolism may contribute to variation in response to DOX toxicity.     

Role of mechanistic target of rapamycin (mTOR) in renal function and ischaemia–reperfusion induced kidney injury

Despite the presence of many studies on the role of mechanistic target of rapamycin (mTOR) in cardiorenal tissues, the definitive role of mTOR in the pathogenesis of renal injury subsequent to ischaemia–reperfusion (IR) remains unclear. The aims of the current study were to characterize the role of mTOR in normal kidney function and to investigate the role of mTOR activation in IR‐induced kidney injury. In euvolemic anaesthetized rats, treatment with the mTOR inhibitor rapamycin increased blood pressure (121 ± 2 to 144 ± 3 mmHg; P<.05), decreased glomerular filtration rate (GFR; 1.6 ± 0.3 to 0.5 ± 0.2 mL/min; P<.05) and increased urinary sodium excretion (UNaV; 14 ± 1 to 109 ± 25 mmol/L per hour; P<.05). In rats subjected to IR, autophagy induction, p‐mTOR expression and serum creatinine increased (1.9 ± 0.2 to 3 ± 0.3 mg/dL; P<.05); treatment with rapamycin blunted p‐mTOR expression but further increased autophagy induction and serum creatinine (3 ± 0.3 to 5 ± 0.6 mg/dL; P<.05). In contrast, clenbuterol, an mTOR activator, blunted the effect of rapamycin on serum creatinine (4 ± 0.6 vs 2.3 ± 0.3 mg/dL; P<.05), autophagy induction and p‐mTOR expression. IR also increased 24 hour protein excretion (9 ± 3 to 17 ± 2 mg/day; P<.05) and kidney injury molecule‐1 (KIM‐1) expression, and rapamycin treatment further increased KIM‐1 expression. Clenbuterol exacerbated protein excretion (13 ± 2 to 26 ± 4 mg/day; P<.05) and antagonized the effect of rapamycin on KIM‐1 expression. Histopathological data demonstrated kidney injury in IR rats that was worsened by rapamycin treatment but attenuated by clenbuterol treatment. Thus, mTOR signalling is crucial for normal kidney function and protecting the kidney against IR injury through autophagy suppression.     

Preventive effects of a fractioned polysaccharide from a traditional Chinese herbal medical formula (Yu Ping Feng San) on carbon tetrachloride‐induced hepatic fibrosis

Objectives The study was to investigate the prevention effects and possible mechanism of Yu Ping Feng San fractioned polysaccharide (YPF‐P) on CCl₄‐induced liver fibrosis in rats. Methods YPF‐P was prepared from root of Astragalus membranaceus, rhizome of Atractylodes macrocephaia and root of Raidix saposhnikoviae, and compared with polysaccharide from root of Astragalus membranaceus (AP). Hepatic fibrosis was induced by subcutaneous injection with carbon tetrachloride twice weekly for 12 weeks in Sprague–Dawley rats. YPF‐P, AP and colchicine were administered intragastrically daily to carbon tetrachloride‐treated rats. Histopathological changes of the liver and hepatic stellate cells were evaluated by Masson staining and transmission electron microscopy, respectively. Markers of fibrosis were determined by radioimmunoassay, biochemistry assay and ELISA. The mRNA expressions of tissue inhibitor of metalloproteinase‐1 (TIMP‐1), matrix metalloproteinase‐13 (MMP‐13), procollagen I and collagen III were detected by RT‐PCR. Key findings YPF‐P dose‐dependently alleviated the degree of liver fibrosis and inhibited hepatic stellate cell transformation into myofibroblast‐like cells, markedly reduced the elevated levels of hyaluronic acid, laminin, type IV collagen, type III procollagen, hydroxyproline and transforming growth factor beta‐1, suppressed procollagen I, collagen III and TIMP‐1 expression, and improved the TIMP‐1/MMP‐13 ratio. MMP‐13 expression was only promoted moderately by YPF‐P. Compared with AP, YPF‐P showed more potency on most markers except laminin, type IV collagen and MMP‐13 mRNA. Conclusions YPF‐P prevented the progress of rat liver fibrosis induced by carbon tetrachloride and had a more potent preventative effect. The preventative effect may be associated with the ability of YPF‐P to inhibit the synthesis of matrix collagen and balance the TIMP/MMP system.     

二氧化硫对自发性高血压大鼠血压及血管结构的影响

目的研究二氧化硫(SO2)对自发性高血压大鼠(spontaneously hypertensive rat,SHR)血压以及平滑肌细胞增殖的影响。方法4wk♂SHR16只,随机分为SHR对照组(n=8)、SHR+Na2SO3/NaHSO3组(n=8),同样周龄(n=8)正常血压的Wistar-Kyoto(WKY)大鼠8只为正常对照组。5wk后检测各组大鼠血压,应用图像采集与分析系统对Hart′s改良弹力纤维染色的胸主动脉显微形态结构做定量分析,应用免疫组织化学方法检测平滑肌细胞增殖指数。结果9wk时SHR对照组血压高于WKY对照组大鼠(P<0·01);SHR+Na2SO3/NaHSO3组大鼠的血压较SHR对照组降低(P<0·01)。SHR对照组左心室与全心重量比高于WKY对照组大鼠(P<0·05)。SHR对照组胸主动脉中膜厚度与内径之比高于WKY对照组大鼠(P<0·01)。SHR+Na2SO3/NaHSO3组大鼠胸主动脉的中膜压力、中膜厚度与内径之比低于SHR对照组大鼠(P<0·01)。SHR对照组主动脉平滑肌细胞PI高于WKY对照组大鼠(P<0·01),SHR+Na2SO3/NaHSO3组PI低于SHR对照组(P<0·01)。结论SO2通过扩张血管和抑制血管平滑肌细胞增殖,参与缓解自发性高血压的形成及主动脉结构重塑。     

Dual effects of amiodarone on pacemaker currents in hypertrophied ventricular myocytes isolated from spontaneously hypertensive rats

The pacemaker current I_f conducted by hyperpolarization‐activated cyclic nucleotide‐gated (HCN) channels plays a critical role in the regulation of cardiac automaticity, with I_f density increased in hypertrophied ventricular myocytes. Amiodarone, a highly effective anti‐arrhythmic agent, blocks human HCN currents and native I_f under normal conditions. To determine the effects of amiodarone under pathological conditions, we monitored I_f under after both acute (0.01, 0.1, 1, 10 and 100 μmol/L) and chronic (10 μmol/L) amiodarone treatment in ventricular myocytes from spontaneously hypertensive rats (SHR) with left ventricular hypertrophy using the whole‐cell patch‐clamp technique. The I_f current density was significantly greater in SHR ventricular myocytes than in cells from healthy normotensive control Wistar‐Kyoto (WKY) rats. Acute application of amiodarone significantly decreased I_f density in myocytes from both SHR and WKY rats. The inhibition was concentration dependent with an IC₅₀ of 4.9 ± 1.2 and 6.9 ± 1.3 μmol/L in myocytes from SHR and WKY rats, respectively. Amiodarone increased the activation and deactivation times of I_f in myocytes from SHR, although it did not alter the relationship of voltage‐dependent activation and the reversal potential of I_f in myocytes from SHR. Chronic exposure of myocytes from SHR to amiodarone potently inhibited I_f and downregulated HCN2 and HCN4, the major channel subtypes underlying native I_f, at both the mRNA and protein level. These findings indicate that amiodarone inhibits I_f under hypertrophied conditions through dual mechanisms: (i) direct channel blockade of I_f currents; and (ii) indirect suppression via negative regulation of HCN channel gene expression. These unique properties of amiodarone may contribute to its anti‐arrhythmic properties under pathological conditions.     

Use of the operational model of agonism and [3H]prazosin binding to assess altered responsiveness of α1-adrenoceptors in the vas deferens of spontaneously hypertensive rat

Changes in functional responsiveness to α₁-adrenoceptor activation with noradrenaline and in [³H]prazosin binding in the epididymal portion of vas deferens from normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were investigated. The operational model fitting and the nested hyperbolic method were used to analyze the effects of irreversible receptor alkylation by phenoxybenzamine (0.1 μM) on the α₁-adrenoceptor mediated contractile responses to noradrenaline of vasa deferentia from SHR and WKY rats. Saturation isotherms for [³H]prazosin revealed a significant increase (P < 0.05) in the B_max in SHR vas deferens (145 ± 19 fmol/mg protein) compared with vas deferens from normotensive controls (75 ± 12 fmol/mg protein) without changes in the K_D. No differences in the proportion of high and low affinity binding sites for WB-4101 and 5-methylurapidil were observed. The maximum contractile response, α, (P < 0.001) and the pEC₅₀ (P < 0.05) values for noradrenaline were greater for SHR than for WKY rat tissues. The apparent affinity (pK_A) determined by the nested hyperbolic method and by the operational model of agonism was found to be similar in the two strains. In agreement with relative pEC₅₀, the efficacy (τ) value for SHR was greater than for WKY rats. However, the difference in the τ estimates did not reach statistical significance. In summary, in the epididymal portion of SHR vas deferens, the increased maximum contractile response to noradrenaline is due to an increase of E_m. Taken together, the τ values and the results from binding experiments lead to the assumption that the transducer constant K _E must be greater in SHR than in WKY rats, suggesting a deterioration in the transduction of the stimulus provided by the agonist in hypertensive animals. Received: 28 November 1996 / Accepted: 27 March 1997