Altered NADH and improved function by anesthetic and ischemic preconditioning in guinea pig intact hearts

Abstract

NADH increases during ischemia because O2 shortage limits NADH oxidation at the electron transport chain. Ischemic (IPC) and anesthetic preconditioning (APC) attenuate cardiac reperfusion injury. We examined whether IPC and APC similarly alter NADH, i.e., mitochondrial metabolism. NADH fluorescence was measured at the left ventricular wall of 40 Langendorff-prepared guinea pig hearts. IPC was achieved by two 5-min periods of ischemia and APC by exposure to 0.5 or 1.3 mM sevoflurane for 15 min, each ending 30 min before 30 min of global ischemia. During ischemia, NADH initially increased in nonpreconditioned control hearts and then gradually declined below baseline levels. This increase in NADH was lower after APC but not after IPC. The subsequent decline was slower after IPC and APC. On reperfusion, NADH was less decreased after IPC or APC, mechanical and metabolic functions were improved, and infarct size was lower compared with controls. Our results indicate that IPC and APC cause distinctive changes in mitochondrial metabolism during ischemia and thus lead to improved function and tissue viability on reperfusion.experimental; infarction; sevoflurane; dose dependency; mitochondrial function EXPERIMENTS IN ISOLATED MYOCYTES, intact hearts, and whole animal models have shown that cardiac cell injury and mechanical dysfunction are caused by reperfusion after prolonged ischemia. Depending on the duration and magnitude of the ischemia, the injury can be reversible (stunning) or irreversible (infarction) (20). Several interrelated mechanisms are responsible:

Proteção miocárdica pelo pré- e pós-condicionamento anestésico

“…On the other hand, oxidation of succinate was not affected, indicating that those agents do not affect complexes II and IV. Those results are in agreement with another study in which the administration of sevoflurane increased the concentration of NADH in isolated guinea pigs hearts 76 . The attenuation of respiration in complex I induced by sevoflurane in isolated mitochondria of guinea pigs was abolished by free radicals scanvengers 77 .…”

“…A abertura dos canais de KATP dependentes também pode reduzir a permeabilidade transitória da membrana mitocondrial e prevenir a apoptose e ou a necrose. PROTEÇÃO MIOCÁRDICA PELO PRÉ-E PÓS-CONDICIONAMENTO ANESTÉSICO estão de acordo com outro estudo no qual a administração de sevoflurano aumentou a concentração de NADH em corações isolados de cobaias 76 . A atenuação da respiração no complexo I, induzida pelo sevoflurano em mitocôndrias isoladas de cobaias, foi abolida por varredores de radicais livres 77 .…”

O2delivery and redox state are determinants of compartment-specific reactive O2species in myocardial reperfusion

“…Previous studies have utilized autofluorescence spectroscopy methodology to measure NADH in isolated hearts and myocardial tissue (9,19,22). Within the total NAD and NADP pool, NADP makes up ϳ6% of the total pool (24).…”

ROS scavenging before 27°C ischemia protects hearts and reduces mitochondrial ROS, Ca2+ overload, and changes in redox state

“…85-23, Revised 1996) and was approved by the animal studies committee, Medical College of Wisconsin (Milwaukee, WI). Our methods have been described previously (14,16,26,38). Thirty milligrams of ketamine and 1,000 units of heparin were injected intraperitoneally into 120 guinea pigs of either sex (250 -350 g wt).…”

“…NADH and FAD were measured as tissue autofluorescence (auto F) as previously described (1,2,38,48). Tissue auto F at em 460 nm (ex 350 nm) was used to measure changes in mitochondrial NADH, which represents a majority of cellular NADH.…”