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Isolated Aortic Rings (isolated aortic + ring)
Selected AbstractsExposure of rats to hyperoxia enhances relaxation of isolated aortic rings and reduces infarct size of isolated heartsACTA PHYSIOLOGICA, Issue 4 2002P. Tähepõld ABSTRACT Exposure of rats to hyperoxia before organ harvesting protected their isolated hearts against global ischaemia,reperfusion injury in a previous study. The present study investigates whether hyperoxia influences vasomotor function and regional ischaemia of the heart. Isolated rings of the thoracic aorta were obtained from rats immediately or 24 h after in vivo exposure to 60 min of hyperoxia (>95% O2), and the in vitro dose,response to phenylephrine (PHE), prostaglandin F2, (PGF2,) and endothelin-1 (ET-1), acetylcholine (Ach) and sodium nitroprusside (SNP) was assessed. Hyperoxia in vivo increased the relaxation of aortic rings to Ach and SNP, while it delayed contraction to PHE. The effect was more evident when the vessels were harvested immediately rather than 24 h after hyperoxic exposure. In separate experiments rat hearts were isolated immediately after hyperoxia, buffer-perfused, and subjected to 30 min of regional ischaemia and reperfused for 120 min. Infarct size was determined by triphenyl tetrazolium chloride staining. Hyperoxia significantly reduced infarct size. In normoxic controls 23.0 ± 8.3% of the area at risk was infarcted, while in hyperoxic animals infarct size was 14.8 ± 5.6% of the area at risk (P = 0.012). Exposure of rats to hyperoxia modifies the vasomotor response of isolated aortic rings, and reduces the infarct size of isolated rat heart. These novel aspects of hyperoxic treatment require further studies to explore the potential of its clinical application. [source] Relationship between protective effects of rosiglitazone on endothelium and endogenous nitric oxide synthase inhibitor in streptozotocin-induced diabetic rats and cultured endothelial cellsDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 2 2007Shan Wang Abstract Background Previous investigations have indicated that the level of asymmetric dimethylarginine (ADMA) is increased in diabetic patients and animals, and rosiglitazone has a protective effect on the endothelium. In the present study, we tested the relationship between protective effects of rosiglitazone and ADMA in streptozotocin (STZ)-induced diabetic rats and cultured endothelial cells. Methods Blood samples were collected from carotid artery. Vasodilator responses to acetylcholine (ACh) in the isolated aortic rings were measured, and serum concentrations of glucose, lipid, nitrite/nitrate, ADMA and tumour necrosis factor-, (TNF-,) were determined. Cultured endothelial cells were treated with ADMA, and the concentrations of intercellular adhesion molecule (ICAM-1), TNF-,, and the activity of nuclear factor-,B (NF-,B) were determined. Results Vasodilator responses to ACh were decreased markedly and the serum concentrations of TNF-,, nitrite/nitrate and ADMA were increased significantly in diabetic rats. Rosiglitazone (3, 10 or 30 mg/kg) produced a significant reduction of the inhibition of vasodilator responses to ACh, but had no effect on the serum concentrations of glucose, lipid, nitrite/nitrate and ADMA in diabetic rats. ADMA (30 µM) significantly increased the activity of NF-,B and elevated the levels of ICAM-1 and TNF-,, and pre-treatment with rosiglitazone (10 or 30 µM) markedly inhibited the increased activity of NF-,B and reduced the elevated levels of TNF-, and ICAM-1 induced by ADMA in cultured endothelial cells. Conclusions Rosiglitazone improves endothelial function in diabetic rats, which is related to the reduction of the inflammatory response induced by ADMA. Copyright © 2006 John Wiley & Sons, Ltd. [source] Aerobic exercise acutely improves insulin- and insulin-like growth factor-1-mediated vasorelaxation in hypertensive ratsEXPERIMENTAL PHYSIOLOGY, Issue 5 2010Ai-Lun Yang Limited information is available concerning the effects of aerobic exercise on vasorelaxation in hypertension. The aim of this study was to investigate the effects of a single bout of aerobic exercise on insulin- and insulin-like growth factor-1 (IGF-1)-induced vasorelaxation in hypertensive rats. Four-month-old spontaneously hypertensive rats were randomly divided into a sedentary group (SHR) and an exercise group (SHR+Ex) subjected to a single bout of aerobic exercise conducted by treadmill running at 21 m min,1 for 1 h. Age-matched Wistar,Kyoto rats were used as a normotensive control group (WKY). Insulin- and IGF-1-induced vasorelaxant responses in the three groups were evaluated by using isolated aortic rings, with or without endothelial denudation, in organ baths. Possible roles of phosphatidylinositol 3-kinase (PI3K) and nitric oxide synthase (NOS) involved in the NO-dependent vasorelaxation were examined by adding selective inhibitors. The role of superoxide was also clarified by adding superoxide dismutase (SOD). In addition, the endothelium-independent vascular responses to sodium nitroprusside (SNP), a NO donor, were examined. The insulin- and IGF-1-induced vasorelaxation was significantly (P < 0.05) decreased in the SHR group compared with the WKY group. This decreased response in SHR was improved by exercise. These vasorelaxant responses among the three groups became similar after endothelial denudation and pretreatment with the PI3K inhibitor, NOS inhibitor or SOD. Also, no difference among groups was found in the SNP-induced vasorelaxation. We concluded that a single bout of aerobic exercise acutely improves insulin- and IGF-1-mediated vasorelaxation in an endothelium-dependent manner in hypertensive rats. [source] Citrulline does not relax isolated rat and rabbit vesselsBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2000Stephen Marx The study was prompted by the report of Ruiz E. & Tejerina T., 1998 describing endothelium-independent relaxation by L-citrulline via activation of particulate guanylate cyclase. We compared the effects of L-citrulline and L -arginine in isolated aortic rings of rats and in isolated aortic, carotid and femoral artery rings of rabbits. No significant relaxation to either L-citrulline or L -arginine was found in the concentration range of 10,12 to 10,3 M, while 3-morpholinosydnonimine hydrochloride (SIN-1, 10,6 M) relaxed vascular tissues. This study does not support the conclusion that L-citrulline has direct vasorelaxing action on vascular smooth muscle. British Journal of Pharmacology (2000) 130, 713,716; doi:10.1038/sj.bjp.0703372 [source] | |||||||||||||