Effects of captopril and angiotensin II receptor blockers (AT1, AT2) on myocardial ischemia-reperfusion induced infarct size.

The renin-angiotensin system (RAS) plays a major role in regulating the cardiovascular system, and disorders of the RAS contribute largely to the cardiac pathophysiology, including myocardial ischemia-reperfusion (MI/R) injury. Two subtypes of angiotensin II (Ang II) receptors have been defined on the basis of their differential pharmacological properties. The current study was undertaken to address the question as to whether the inhibition of the angiotensin converting enzyme (ACE) by captopril and the AT1 and AT2 receptor blockers losartan and PD123319 modulate MI/R-induced infarct size in an in vivo rat model. To produce necrosis, a branch of the descending left coronary artery was occluded for 30 min followed by two hours of reperfusion. ECG changes, blood pressure, and heart rate were measured during the experiment. Captopril (3 mg/kg), losartan (2 mg/kg), and PD123319 (20 μg/kg/min) were given in an IV 10 min before ischemia and were continued during the ischemic period. The infarcted area was measured by TTC staining. The volume of infarct and the risk zone was determined by planimetry. Compared to the control group (55.62±4.00%) both captopril and losartan significantly reduced the myocardial infarct size (30.50±3.26% and 37.75±4.44%), whereas neither PD123319 nor PD123319+losartan affected the infarct size volume (46.50±3.72% and 54.62±2.43%). Our data indicates that captopril and losartan exert cardioprotective activity after an MI/R injury. Also, infarct size reduction by losartan was halted by a blockade of the AT2 receptor. Therefore, the activation of AT2 receptors may be potentially protective and appear to oppose the effects mediated by the AT1 receptors.

Parlakpinar H ，Ozer MK ，Acet A 《-》

Effects of captopril and losartan on myocardial ischemia-reperfusion induced arrhythmias and necrosis in rats.

Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 (AT (1)) receptor blockers improve ischemia-reperfusion induced arrhythmias and infarct size in several animal models. However, the effects of pretreatment with ACEIs or AT (1) receptor blockers on acute myocardial infarct size and arrhythmias are controversial. Thus, we sought to assess the comparative effects of pretreatment with ACEI captopril and AT (1)-receptor blocker losartan on myocardial infarct size and arrhythmias in a rat model of ischemia-reperfusion. We randomly assigned 92 male Wistar rats for arrhythmias ( n= 60) and necrosis ( n= 32) experiments. To produce arrhythmia, the left main coronary artery was occluded for 7 min, followed by 7 min of reperfusion and to produce necrosis, the the left main coronary artery was occluded for 30 min, followed by 120 min of reperfusion. Captopril (3 mg kg (-1)) and losartan (0.2 and 2 mg kg (-1)) were given intravenously 10 min before occlusion. Captopril reduced the incidences of ventricular fibrillation (VF) and mortality associated with irreversible VF, whereas the studied doses of losartan did not. Captopril also decreased the number of ventricular beats on reperfusion. Losartan 2 mg kg (-1) reduced both the number of ventricular premature beats and the incidence of ventricular tachycardia (VT) on reperfusion, while losartan at dose of 0.2 mg kg (-1) had no effect on these arrhythmias. Compared to the control group, both captopril and losartan reduced myocardial infarct size in the rat model of ischemia-reperfusion, but this was statistically significant for captopril only. In this experimental model, although captopril did not reduce the incidence of reperfusion-induced VT, it was more effective than the AT (1)-receptor blocker losartan at preventing mortality associated with irreversible VF and to reduce myocardial infarct size in rat model of ischemia-reperfusion.

Ozer MK ，Sahna E ，Birincioglu M ，Acet A ... -  《PHARMACOLOGICAL RESEARCH》

Comparison of the effects of losartan, captopril, angiotensin II type 2 receptor agonist compound 21, and MAS receptor agonist AVE 0991 on myocardial ischemia-reperfusion necrosis in rats.

Myocardial ischemia may occur as a result of pathophysiological and therapeutical applications such as atherosclerosis, thromboembolism, percutaneous transluminal coronary angioplasty, coronary artery bypass, and transplantation. In this study, we aimed to compare the effects of angiotensin (Ang) II type 2 (AT2 ) selective receptor agonist Compound 21 (C21), MAS receptor agonist AVE 0991, Ang II type 1 (AT1 ) selective receptor blocker losartan, and Ang-converting enzyme inhibitor captopril on haemodynamic parameters and infarct size on myocardial ischemia/reperfusion (MI/R)-induced necrosis in rats. To induce necrosis in the heart of rats, reperfusion for 2 h following ischemia for 30 min to the descending branch of the left main coronary artery was achieved. C21 (0.03 mg/kg), AVE 0991 (576 μg/kg), losartan (2 mg/kg), and captopril (3 mg/kg) were administered as an intravenous infusion at 10 min before and throughout the ischemia. Then, the infarct size and risk area were calculated from the heart. The percentage of myocardial infarct size to area at risk ratio (%IS/AR) of groups was Control (MI/R) group: 48.9 ± 8.8%; C21 group: 31.1 ± 7.8%; AVE 0991 group: 29.9 ± 4.8%; C21 + AVE 0991 group: 28.2 ± 3.3%; Losartan + AVE 0991 group: 30.8 ± 5.8%; Captopril + AVE 0991 group: 31.7 ± 7.7%. %IS/AR of the drug-treated groups decreased significantly when compared to the MI/R group (P < 0.05). Our results indicate that the importance of AT1 , AT2 , and MAS receptors in the MI/R injury. Inhibition of Ang II formation by captopril, blockade of AT1 receptor with losartan, and stimulation of AT2 receptor with C21 and MAS receptor with AVE 0991 showed beneficial effects by reducing infarct size.

Ozhan O ，Parlakpinar H ，Acet A 《-》

Tissue kallikrein is involved in the cardioprotective effect of AT1-receptor blockade in acute myocardial ischemia.

Messadi-Laribi E ，Griol-Charhbili V ，Pizard A ，Vincent MP ，Heudes D ，Meneton P ，Alhenc-Gelas F ，Richer C ... -  《JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS》

Comparative effects of aspirin with ACE inhibitor or angiotensin receptor blocker on myocardial infarction and vascular function.

Zhu BQ ，Sievers RE ，Browne AE ，Lee RJ ，Chatterjee K ，Grossman W ，Karliner JS ，Parmley WW ... -  《JOURNAL OF THE RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM》