Arterial remodeling in chronic sinoaortic-denervated rats

The spontaneous variation of blood pressure is defined as "blood pressure variability" (BPV). The chronic sinoaortic-denervated (SAD) rat is a model of high BPV without sustained hypertension. Little is known about vascular remodeling in this model. In the present study, we examined blood pressure, vascular remodeling, and aortic angiotensin II concentration in chronic SAD rats in separate experiments. In experiment 1, intra-arterial blood pressure was continuously recorded in conscious unrestrained rats. The 16-week SAD rats had a significant increase in BPV and no change in the mean level of blood pressure over a 24-h period. In experiment 2, we measured structural changes of seven kinds of arteries by histologic method and computer image analysis and functional changes of thoracic aortas by isolated artery preparation. Structural remodeling after 16-week sinoaortic denervation was characterized by increase in wall thickness, wall area, and ratio of wall thickness to internal diameter, with different changes in internal diameter and external diameter in different arteries, indicating that arterial structural remodeling expresses itself mainly as vascular growth. This vascular growth might be caused by medial smooth muscle cell growth and collagen accumulation. Aortic contraction induced by norepinephrine was potentiated, whereas aortic relaxation induced by acetylcholine was attenuated after sinoaortic denervation. In experiment 3, plasma and aortic angiotensin II concentrations were determined by radioimmunoassay. The former remained unchanged, whereas the latter was significantly increased in 10-week SAD rats. It is concluded that in rats chronic sinoaortic denervation can produce vascular remodeling that might be related to increased BPV and an activated tissue renin-angiotensin system.     

去窦弓神经大鼠的胸主动脉重构

目的　观察大鼠去窦弓神经 (SAD)后由于血压不稳定而引起的血管重构。方法　 10wk大鼠行SAD或Sham ,术后 16周用离体动脉环实验测定SAD和相应Sham组大鼠胸主动脉对去甲肾上腺素 (NE)和氯化乙酰胆碱 (Ach)的收缩和舒张反应 ;用组织病理学和计算机图像分析技术对大鼠的胸主动脉连续切片进行观察和比较。结果　与Sham组相比 ,SAD大鼠离体胸主动脉环对NE的收缩反应增强 ,对Ach的舒张反应减弱 ;SAD组大鼠胸主动脉的结构改变主要以血管中层平滑肌细胞肥大和基质扩充为主。结论　大鼠去窦弓神经后单纯血压不稳定可引起血管重构     

Erdosteine prevents bleomycin-induced pulmonary fibrosis in rats

Oxidative stress plays an important role in the pathogenesis of idiopathic pulmonary fibrosis. Therefore, erdosteine, an antioxidant, is expected to have an inhibitor potential against the disease. Rats were given one dose of bleomycin in pulmonary fibrosis groups and saline in controls. The first dose of oral erdosteine (10 mg/kg/day) was given 2 days before the bleomycin injection to achieve the plateau level in blood and continued until killing. At day 14, fibrotic changes were evaluated, using Aschoft's criteria and lung hydroxyproline content. Bleomycin produced a fivefold increase in fibrosis score that was decreased by 87% by erdosteine (P>0.001) and almost twofold increases in hydroxyproline content which were completely prevented by erdosteine. Myeloperoxidase activities and MDA levels, which were significantly higher in the bleomycin group, were then significantly attenuated by erdosteine. These results revealed that oral erdosteine may prevent the development of acute pulmonary inflammation caused by bleomycin injection via the repression of neutrophil accumulation and lipid peroxidation, resulting in the inhibition of subsequent lung fibrosis.     

Tetrandrine prevents monocrotaline-induced pulmonary hypertension in rats

In this study, the effects of chronic administration of tetrandrine (TET) on monocrotaline (MCT) induced pulmonary hypertension were investigated. The results showed that MCT induced marked pulmonary hypertension and right ventricular hypertrophy; TET 50 mg kg⁻¹ and 100 mg kg⁻¹ significantly decreased pulmonary artery pressure (Ppa, from 5.2 ± 0.48 kPa to 4.35 ± 0.69 kPa, P < 0.05 and to 3.79 ± 0.84 kPa, P < 0.05, respectively) without marked influence on systemic arterial pressure (Psa). TET restored right ventricular hypertrophy (right ventricular index significantly decreased from 0.41 to 0.37 and 0.32, respectively). Histological findings showed that TET restored MCT-induced lung tissues and vascular lesion and pulmonary arteries media hypertrophy. We conclude that chronic administration of TET does have selective effects on pulmonary hypertension produced by MCT. Drug Dev. Res. 39:158–160. © 1997 Wiley-Liss, Inc.     

L-精氨酸对高肺血流所致肺血管结构重建的调节

目的　探讨L 精氨酸 (L Arg)对高肺血流所致肺血管结构重建的作用及其机制。方法　 2 0只Sprague Dawley大鼠随机分为对照组 (n =6 )、分流组 (n =7)和分流 +L Arg组 (n =7)。对分流组和分流 +L Arg组大鼠行腹主动脉 -下腔静脉分流术。对分流 +L Arg组大鼠每天予L Arg 1g·kg-1灌胃。 11wk后 ,以右心导管法测定肺动脉平均压(mPAP) ;检测右心室 /左心室 +室间隔 (RV/LV +S)比值 ;观测肺血管显微和超微结构的变化 ;免疫组织化学方法检测肺动脉人类尾加压素II(hUII)的表达。结果　分流组大鼠mPAP和RV/LV +S比值明显高于对照组 (P均 <0 0 1) ,并且肺动脉显微和超微结构发生明显改变。分流组大鼠肺动脉内皮细胞和平滑肌细胞hUII表达明显增强。分流 +L Arg组大鼠mPAP和RV/LV +S比值明显低于分流组 (P均<0 0 5 )。L Arg缓解了肺血管结构重建的形成 ,同时明显抑制了分流大鼠肺动脉hUII的表达。结论　L Arg抑制肺动脉内皮细胞和平滑肌细胞新型血管活性肽hUII表达 ,可能参与高肺血流所致肺血管结构重建及肺动脉高压的调节     

Calcium antagonist verapamil prevented pulmonary arterial hypertension in broilers with ascites by arresting pulmonary vascular remodeling

Calcium signaling has been reported to be involved in the pathogenesis of hypertension. Verapamil, one of the calcium antagonists, is used to characterize the role of calcium signaling in the development of pulmonary arterial hypertension syndrome in broilers. The suppression effect of verapamil on pulmonary arterial hypertension and pulmonary vascular remodeling was examined in broilers, from the age of 16 days to 43 days. Our results showed that oral administration of lower dose of verapamil (5 mg/kg body weight every 12 h) prevented the mean pulmonary arterial pressure, the ascites heart index and the erythrocyte packed cell volume of birds at low temperature from increasing, the heart rate from decreasing, and pulmonary arteriole median from thickening, and no pulmonary arteriole remodeling in broilers treated with the two doses of verapamil at low temperature was observed. Our results indicated that calcium signaling was involved in the development of broilers' pulmonary arterial hypertension, which leads to the development of ascites, and we suggest that verapamil may be used as a preventive agent to reduce the occurrence and development of pulmonary arterial hypertension in broilers.     

Amlodipine prevents monocrotaline-induced pulmonary arterial hypertension and prolongs survival in rats independent of blood pressure lowering

1. The present study was designed to examine the role of amlodipine in preventing and reversing monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) in rats. 2. Rats were injected with MCT (40 mg/kg, s.c.) and randomly given either 6 mg/kg per day of amlodipine in drinking water or placebo for 3 weeks. Any animals treated with MCT that survived for 3 weeks were given either amlodipine or placebo for the next 3 weeks. 3. Blood pressure was not different between the groups. Amlodipine immediately following MCT markedly inhibited PAH with severe pulmonary vascular remodelling. The survival rate at 3 weeks after treatment was increased significantly in the amlodipine group compared with the placebo group (77%vs 43%; P < 0.01). The placebo group showed markedly diminished expression of endothelial nitric oxide synthase (eNOS) protein and mRNA levels, increased numbers of proliferating cell nuclear antigen-positive cells, enhanced mRNA expression of matrix metalloproteinase-2 and pro-inflammatory cytokines in the lung tissue and upregulation of P-selectin on the endothelium of the pulmonary arteries, whereas these effects were suppressed in the amlodipine-treated group. Furthermore, late treatment with amlodipine did not palliate PAH or improve survival. 4. Amlodipine inhibited the development of PAH and improved survival in rats independent of its effect on lowering blood pressure. These effects were associated with marked inhibition of the downregulation of eNOS and improvement of pulmonary vascular endothelial activation, as well as anti-inflammatory, antiproliferative and antifibrotic effects in the lung tissue. However, amlodipine failed to reverse established PAH. This study may provide an insight into therapeutic strategy of amlodipine in PAH.     

Inhibition of cyclooxygenase-2 prevents adverse effects induced by phosphodiesterase type 4 inhibitors in rats

BACKGROUND AND PURPOSE

Phosphodiesterase type 4 (PDE4) inhibitors such as roflumilast are currently being developed as anti-inflammatory treatments for chronic airway disorders. However, high doses of PDE4 inhibitors have also been linked to several side effects in different animal species, including pro-inflammatory effects in the rat. Here, we analysed PDE4-related toxicological findings in a rat model and how these side effects might be therapeutically prevented.

EXPERIMENTAL APPROACH

Wistar rats were treated orally once daily with 10 mg·kg⁻¹ roflumilast for 4 days. Macroscopic changes were monitored throughout the study and further parameters were analysed at the end of the experiment on day 5. In addition, the effects of concomitant treatment with cyclooxygenase (COX) inhibitors were assessed.

KEY RESULTS

Supratherapeutical treatment with roflumilast induced marked body and spleen weight loss, diarrhea, increased secretory activity of the harderian glands, leukocytosis, increased serum cytokine-induced neutrophil chemoattractant-1 (CINC-1) levels, and histopathological changes in thymus, spleen, mesentery and mesenteric lymph nodes. All these toxicological findings could be prevented by the non-steroidal anti-inflammatory drug (NSAID) and non-selective COX inhibitor, diclofenac, given orally. Similar protective effects could be achieved by the COX-2 selective inhibitor lumiracoxib, whereas the COX-1 selective inhibitor SC-560 was generally not effective.

CONCLUSIONS AND IMPLICATIONS

Treatment with an NSAID inhibiting COX-2 prevents the major effects found after subchronic overdosing with the PDE4-specific inhibitor roflumilast. If this effect translates into humans, such combined treatment may increase the therapeutic window of PDE4 inhibitors, currently under clinical development.     

Combined effects of the ATP-sensitive potassium channel opener pinacidil and simvastatin on pulmonary vascular remodeling in rats with monocrotaline-induced pulmonary arterial hypertension

The drugs that are currently used to treat pulmonary hypertension (PH) lack the ability to inhibit or reverse the pulmonary vascular remodeling that occurs during the course of the disease. We propose a novel method that combines the therapeutic powers of the potassium channel opener pinacidil and the statin drug simvastatin. These two drugs do not share similar mechanisms of treating PH. We used rats with monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) as a model and examined the combined effects of pinacidil and simvastatin on pulmonary vascular remodeling. A series of indicators, including those for pulmonary vascular obstruction, proliferation, and cell phenotype, pulmonary vascular matrix and pulmonary vascular smooth muscle cell phenotype were used to monitor changes in pulmonary structure over the course of disease and treatment in normal controls, untreated PAH rats, pinacidil-treated subjects, simvastatin-treated subjects, and combination-treated subjects. We found that levels of mPAP, right ventricle Fulton index, pulmonary arteriolar wall thickness and muscularization, cell growth rate, transforming growth factor beta (TGF-beta), lung tissue matrix metalloproteinase-2 (MMP-2), MMP-9 and lung tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), vascular smooth muscle cell (VSMC) contractile protein SM-alpha-actin, and SM-alpha-actin mRNA of these different groups were all significantly lower in the combination-treated group than in the untreated group. Subjects in the combination-treated group also showed lower levels than those in either the pinacidil-treated or simvastatin-treated group. These results support our hypothesis and provide basis for a new, more effective therapeutic methods of treating PAH in human patients.     

Greater hypertrophy in right than left ventricles is associated with pulmonary vasculopathy in sinoaortic-denervated Wistar-Kyoto rats

1. Biventricular hypertrophy has been described in a high blood pressure variability (BPV) model of sinoaortic-denervated (SAD) rats without systemic hypertension. To explore the possible involvement of the lung in SAD-induced right ventricular hypertrophy (RVH), we examined lung morphology, in addition to systemic haemodynamics and ventricle morphology, in Wistar-Kyoto rats 32 weeks after SAD. 2. In Wistar-Kyoto rats 32 weeks after SAD, there existed a substantial elevation in BPV, with no change in the average level of arterial pressure. Biventricular hypertrophy following SAD was characterized by a greater hypertrophy in right than left ventricles; both absolute and normalized right ventricular weights were significantly increased by 22 and 27%, respectively, and only normalized left ventricular weight was significantly increased by 12%. No infarcts were found in any ventricles examined. 3. In the lung, the most prominent change following SAD was pulmonary vasculopathy, including wall thickening, perivascular fibrosis and cell infiltration. In pulmonary arteries with an internal diameter of 70-130 microm, the external diameter, wall thickness and wall thickness to internal diameter ratio were increased in SAD compared with control rats. 4. There was no correlation between right and left ventricular weights. In contrast with BPV-correlated left ventricular weight, right ventricular weight was correlated with the wall thickness of the pulmonary artery, but not with BPV. 5. These findings suggest that greater RVH following SAD is associated with pulmonary vasculopathy, but is not secondary to the left ventricular problems or high BPV.     

Sodium hydrosulfide alleviated pulmonary vascular structural remodeling induced by high pulmonary blood flow in rats

AIM: To explore the possible role of endogenous hydrogen sulfide (H(2)S), a novel gasotransmitter, in the pathogenesis of pulmonary vascular structural remodeling (PVSR) induced by high pulmonary blood flow. METHODS: Thirty-two Sprague-Dawley male rats were randomly divided into sham, shunt, sham+NaHS (a H(2)S donor) and shunt+NaHS groups. Rats in shunt and shunt+NaHS groups underwent an abdominal aorta-inferior vena cava shunt, and rats in shunt+NaHS and sham+NaHS groups were intraperitoneally injected with NaHS. PVSR was investigated using optical microscope and transmission electron microscope. Lung tissue H(2)S was evaluated by sulfide-sensitive electrodes. Nitric oxide synthase (NOS), heme oxygenase (HO-1), proliferative cell nuclear antigen (PCNA) and extracellular signal-regulated kinase (ERK) activation were analyzed by Western blotting. RESULTS: After 11 weeks of shunting, PVSR developed with a decrease in lung tissue H(2)S production and an increase in nitric oxide (NO). However, lung tissue carbon monoxide (CO) did not change. After the treatment with NaHS for 11 weeks, H(2)S donor ameliorated PVSR and downregulated PCNA expression and ERK activation with an increase in lung tissue CO production and HO-1 protein expression but a decrease in NO production, NOS activity and eNOS protein expression in shunted rats. CONCLUSIONS: H(2)S exerted a regulatory effect on PVSR induced by high pulmonary blood flow. Meanwhile, H(2)S down-regulated the ERK/MAPK signal pathway, inhibited the NO/NOS pathway and enhanced the CO/HO pathway in rats with high pulmonary blood flow.     

一氧化碳对缺氧性肺血管结构重建大鼠肺动脉转移生长因子表达的影响

目的探讨一氧化碳对缺氧性肺血管结构重建大鼠肺动脉中转移生长因子（TGF）表达的影响。方法将大鼠随机分为3组：常氧组（n=20）、低氧组（n=20）和低氧＋血红素加氧酶组（低氧＋HO组）（n=20）。以光学显微镜观测3组大鼠肺中型动脉及小型动脉的相对中膜厚度（RMT）。应用TGF的单克隆抗体经免疫组织化学技术对3组大鼠肺动脉TGF进行定位及半定量分析。结果低氧组大鼠中型肺动脉及小型肺动脉RMT均高于常氧组和低氧＋HO组（P〈0．01）。3组大鼠各级肺动脉内皮细胞中均有TGF的表达．低氧组高于常氧组和低氧＋HO组（P〈0．01）。中型肺动脉内皮细胞中TGF的表达与相应中型肺动脉RMT之间呈正相关（r为0．7835,P〈0．01）;小型肺动脉内皮细胞中TGF的表达与相应的小型肺动脉RMT之间呈正相关（r为0．8125,P〈0．01）。结论一氧化碳对缺氧性肺血管结构重建大鼠肺动脉中TGF表达有抑制作用。     

Notch信号通路在肺动脉高压肺血管重构中的研究进展

肺动脉高压是一种以肺动脉压力和肺血管阻力持续升高为特征,引起肺血管重构发生的心血管性疾病。Notch信号通路是一种高度保守的信号路径,主要通过调控细胞的增殖、分化及凋亡等过程,参与心血管、神经、肿瘤等疾病的发生、发展。该文主要对Notch信号通路参与肺血管重构发生的分子机制进行综述,以期为肺动脉高压的治疗提供新的策略。     

Central muscarinic involvement in cardiovascular control in sinoaortic-denervated rats

A study was made of the cardiovascular effects of centrally administered cholinergic drugs in conscious sham-operated or sinoaortic-denervated (SAD) rats. Neostigmine (0.01-1 micrograms) and bethanechol (0.125-2 micrograms), injected intracerebroventricularly (i.c.v.), induced a dose-dependent increase in mean blood pressure. This effect was significantly greater in SAD rats than in sham-operated rats. The heart rate was reduced by both neostigmine and bethanechol in sham-operated rats but remained unaltered in SAD animals. Similar doses of neostigmine and bethanechol injected i.v. did not have an effect in sham-operated rats. Central muscarinic blockade with methylatropine (1 or 5 micrograms i.c.v.) prevented the cardiovascular effects induced by neostigmine (1 microgram i.c.v.) in both groups of rats. The administration of methylatropine (0.3 mg/kg i.v.) to sham-operated rats only prevented the bradycardia induced by neostigmine (1 microgram i.c.v.), the pressor response was not affected. These results lend support to the view that cholinergic pathways are involved in the pressor and bradycardic responses of sham-operated rats and that they are mediated through central muscarinic receptors. The bradycardia induced by lower doses of the anticholinesterase, neostigmine, cannot be reflex-mediated. The fact that the pressor response to neostigmine was higher in SAD rats than in sham-operated animals could be either due to a different activity of the cholinergic pathways or to an abolition of baroreflex afferent activity. These results also suggest that there is a connection between central cholinergic pathways and baroreflex efferent activity.     

新型磷酸二酯酶5抑制剂CPD1对肺动脉高压大鼠血管收缩的影响

目的探讨新型磷酸二酯酶5抑制剂CPD1对肺动脉高压(pulmonary arterial hypertension,PAH)大鼠肺动脉和主动脉收缩效应的影响。方法一次性腹腔注射野百合碱(monocrotaline,MCT,50 mg·kg^-1),制备PAH大鼠模型,造模7 d后给予CPD1(10 mg·kg^-1·d^-1)灌胃治疗,持续14 d。通过血管环张力检测技术观察CPD1对MCT致PAH大鼠血管收缩效应的作用。结果成功制备PAH大鼠模型;CPD1治疗可显著降低PAH大鼠右心室收缩压和右心质量指数,改善肺小动脉内膜增生情况,抑制苯肾上腺素(phenylephrine,Phen)和内皮素-1(endothelin-1,ET-1)诱导的PAH大鼠肺动脉和主动脉的收缩效应,而对KCl诱导的血管收缩效应无影响。结论磷酸二酯酶5抑制剂CPD1干预能抑制PAH大鼠模型,其机制可能是CPD1抑制PAH大鼠非电压依赖性钙通道功能,引起血管收缩力降低、血管平滑肌增殖减弱和血管重塑减轻。     

Early structural changes of aortic wall in sinoaortic-denervated rats

1. The present work was designed to observe the early structural changes in the aortic wall in Sprague-Dawley rats 1, 2 and 4 weeks after sinoaortic denervation (SAD). 2. Rats were examined 1, 2 and 4 weeks after SAD. Blood pressure (BP) was recorded in the conscious state. The thoracic aortas were taken for investigations, including: light microscopy, electron microscopy, immunohistochemistry and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labelling (TUNEL). 3. Blood pressure variability (BPV) was significantly increased in the SAD groups 1, 2 and 4 after the operation when compared with the sham-operated ones. 4. Two weeks after SAD the percentage proportion of smooth muscle cell density (SMC%) was obviously increased. 5. Four weeks after SAD: the SMC%, percentage proportion of collagen density (CD%) and aortic wall thickness (WT) were obviously increased with vascular smooth muscle cells blebbing concomitantly. Endothelial cells showed degenerative changes and swelling with blebbing of the cell membrane and increased condensation of peripheral nuclear chromatin and cytoplasmic vacuolization. It was also found that the number of apoptotic endothelial cells was increased and expression of eNOS was reduced. 6. This is the first study that shows the time-course of aortic wall and endothelial cell changes induced by SAD. Increased BPV might be the priming factor in the development of organ damage induced by SAD.     

Morphological evidence of reinnervation of the baroreceptive regions in sinoaortic-denervated rats

1. The arterial baroreflex (ABR) plays an important role in the maintenance of the stability of blood pressure. Sinoaortic denervation (SAD) destroys the integrity of the reflex arc and produces severe organ damage in rats. However, partial recovery of ABR function has been observed following chronic denervation. The aim of the present study was to determine whether there was morphological evidence of reinnervation of the aortic arch and carotid sinus following SAD. 2. A substantial body of physiological and morphological evidence suggests that substance P (SP) may be a neurotransmitter contained in first-order sensory baroreceptor afferents; therefore, the patterns of vascular SP and neurofilament (NF) immunoreactive (IR) innervation of the aortic arch and carotid sinus were investigated in the present study. 3. Ten-week-old male Sprague-Dawley rats underwent SAD or sham operation. Whole mounts of carotid bifurcation and aortic arch were prepared for immunohistochemical study at various time points (1, 9 and 16 weeks after operation). 4. The results of computerized image analysis show that the mean density of NF- and SP-IR nerves of SAD rats 9 and 16 weeks after operation increased gradually and significantly compared with that of rats 1 week after operation. 5. In conclusion, the results indicate that there is reinnervation of the aortic arch and carotid sinus by NF- and SP-IR fibres in SAD rats, which may be the morphological basis for the partial restoration of ABR function over time after SAD.     

Effects of G-CSF on cardiac remodeling and arterial hyperplasia in rats

Although granulocyte colony-stimulating factor (G-CSF) has been shown to prevent cardiac remodeling after acute myocardial infarction, the mechanism and safety of G-CSF treatment acute myocardial infarction remain controversial. The purpose of the present study was to investigate in a rat model the mechanisms underlying the beneficial effect of G-CSF in acute myocardial infarction and to determine whether G-CSF treatment aggravates vascular remodeling of injured artery after acute myocardial infarction. Sprague-Dawley rats received transplanted bone marrow cells from green fluorescent protein (GFP) transgenic rats. Acute myocardial infarction was induced by ligation of the left coronary artery. After 24 h, the right carotid artery was injured with a balloon catheter. G-CSF (100 microg/kg/day) or saline was injected subcutaneously for 5 consecutive days after induction of acute myocardial infarction. G-CSF treatment significantly improved left ventricle function and reduced infarct size in rats with acute myocardial infarction. Expression of mRNA for the angiogenic cytokines was significantly higher in the infarction border area in the G-CSF group than in the control group. The surviving cardiomyocytes in infarction area were more in the G-CSF group. GFP-positive cells were gathered in the infarction border area in both groups; G-CSF did not increase cardiac homing of GFP-positive bone marrow cells in contrast to control group. Most GFP-positive cells were CD68-positive (macrophages). It was difficult to find bone marrow-derived cardiomyocytes in the infarcted area. G-CSF treatment inhibited neointima formation and increased reendothelialization of the injured artery. GFP-positive cells were identified most in the adventitia of the injured artery. A few cells in the neointima and reendothelialization were GFP positive. In conclusion, administration of G-CSF appears to be effective for treatment of left ventricular remodeling after acute myocardial infarction and does not aggravate vascular remodeling. The effect of G-CSF on cardiac and vascular remodeling may occur mainly through a direct action on the heart and arteries.     

Aminoguanidine prevents arterial stiffening and cardiac hypertrophy in streptozotocin-induced diabetes in rats

The formation of advanced glycation endproducts (AGEs) on collagen within the arterial wall may be responsible for the development of diabetic vascular injury. This study was to examine the role of aminoguanidine (AG), an inhibitor of AGEs formation, in the prevention of arterial stiffening and cardiac hypertrophy in streptozotocin (STZ) induced diabetes in rats. Diabetes was induced in animals by a single tail vein injection with 65 mg kg(-1) STZ. After confirmation of the development of hyperglycemia (2 days later), rats were treated for 8 weeks with AG (daily peritoneal injections of 50 mg kg(-1)) and compared with the age-matched untreated diabetic controls. After exposure to AG, the STZ-diabetic rats showed no alterations in cardiac output, aortic pressure profiles, total peripheral resistance, and aortic characteristic impedance. By contrast, treatment of this experimental diabetes with AG resulted in a significant increase in wave transit time (tau), from 20.4+/-0.6 to 24.7+/-0.5 ms (P<0.05) and a decrease in wave reflection factor (R(f)), from 0.78+/-0.04 to 0.53+/-0.02 (P<0.05). The decreased R(f) associated with the increased tau suggest that AG may retard the diabetes-induced augmentation in systolic load of the left ventricle coupled to its arterial system. Meanwhile, the diminished ratio of left ventricular weight to body weight suggests that prevention of the diabetes-related cardiac hypertrophy by AG may correspond to the drug-induced decline in aortic stiffening. Glycation-derived modification on aortic collagen was also found to be enhanced in rats with diabetes (+65.3%, P<0.05) and the advanced glycation process was retarded by AG treatment. We conclude that long-term administration of AG to the STZ-treated rats imparts significant protection against the diabetes-derived deterioration in vascular dynamics, at least partly through inhibition of the AGEs accumulation on collagen in the arterial wall.