Angiotensin II and ischemic preconditioning synergize to improve mitochondrial function while showing additive effects on ventricular postischemic recovery.
Recent studies indicate that the cardioprotective effects of ischemic preconditioning (IPC) against sustained ischemia/reperfusion can be replicated by angiotensin II (Ang II). However, it is not clear whether IPC and Ang II-induced preconditioning (APC) act through similar mechanisms or synergize to enhance cardioprotection. In this study, Langendorff-perfused rat hearts were subjected to IPC, APC, or their combination (IPC/APC) followed by ischemia/reperfusion. IPC, and less potently APC, significantly increased the percent recoveries of the left ventricular developed pressure, the first derivative of developed pressure, and the rate pressure product compared with control. Furthermore, the postischemic recovery of the heart was significantly higher for IPC/APC compared with IPC or APC. The improvements in cardiac function by IPC, APC, and IPC/APC were associated with similar reductions in lactate dehydrogenase release and infarct size. However, a significant improvement in mitochondrial respiration was observed with IPC/APC. The postischemic recovery observed with APC and IPC/APC was inhibited by treatment with losartan, an Ang II type-1 receptor blocker, during the preconditioning phase but not by chelerythrine, a pan-PKC inhibitor. Both drugs, however, abolished the enhanced mitochondrial respiration by IPC/APC. Altogether, these results indicate that APC and IPC interact through mechanisms that enhance cardioprotection by affecting cardiac function and mitochondrial respiration.
Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR.
Rebeca E
RE
Nuñez
Miriam
M
Castro
Sabzali
S
Javadov
Nelson
N
Escobales
D000804:Angiotensin II / Q000378:metabolism*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D010477:Perfusion; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure / Q000187:drug effects
D047228:Angiotensin II Type 1 Receptor Blockers; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D000804:Angiotensin II