Evidence of the role of angiotensin AT(1) receptors in remote renal preconditioning of myocardium.
The underlying mechanisms of myocardial preconditioning after a brief period of renal ischemia-reperfusion are unknown. The phenomenon itself and the involvement of AT(1) angiotensin receptors was therefore investigated using an in vivo rat model of acute myocardial infarction. Anesthetized rats underwent a left thoracotomy and pericardiotomy. A laparotomy was performed to expose the left renal artery. Animals were then preconditioned with four episodes, each consisting of 5 min of renal artery occlusion followed by 10 min of reperfusion, or underwent a 60 min sham period of anesthesia. Subsequently, the left coronary artery was occluded for 30 min and reperfused for 2 h. Area at risk and infarct size was estimated along with hemodynamic and temperature data recording. The infarct-to-risk ratio was limited from 56.36 +/- 2.36 and 50.65 +/- 4.71 in control to 12.0 +/- 0.48 and 12.57 +/- 0.44 in preconditioned hearts, by volume and weight methods. The protective effect of renal preconditioning on the myocardium was not abolished by losartan 1 mg/kg (10.11 +/- 0.12 and 11.2 +/- 1.4) pretreatment whereas it was completely attenuated by losartan 5 mg/kg (46.5 +/- 1.0 and 47.8 +/- 1.4) administration. Thus we can infer that angiotensin AT(1) receptors participate in renal preconditioning of the myocardium in in vivo rat hearts.
Singh
D
D
Pharmacology Division, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India.
Chopra
K
K
D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000502:physiology; D003331:Coronary Vessels / Q000293:injuries; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007275:Injections, Intravenous; D007511:Ischemia / Q000503:physiopathology; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D007668:Kidney / Q000098:blood supply / Q000293:injuries / Q000503:physiopathology*; D019808:Losartan / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000502:physiology*; D012077:Renal Artery / Q000293:injuries; D015424:Reperfusion / Q000379:methods; D013997:Time Factors
D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D019808:Losartan