Is soluble adenylyl cyclase (sAC) involved in ischemia-reperfusion injury?

CIOCCI PARDO, A; MARIANGELO, JI; GONZÁLEZ ARBELÁEZ LF; FANTINELLI JC; AIELLO A; MOSCA SM

Berlin

Congreso; XXIV World Congress International Society for Heart Research. Junio 2022; 2022

ISHR

IntroductionSoluble adenylyl cyclase (sAC) is one of the sources of cAMP. Although the role of sAC in cell signaling has been widely studied, its participation in myocardial ischemia-reperfusion is not clear.ObjectiveTo determine the role played by sAC on myocardial and mitochondrial post-ischemic alterations in isolated rat hearts.Material & methodsIsolated perfused rat hearts were assigned to the following groups: 1) Non-ischemic control (NIC): 110 min of perfusion (P); 2) Ischemic control (IC): 30 min of global ischemia (GI) and 60 min of reperfusion (R), 3) LRE1: 10 μM of LRE1, a specific sAC inhibitor was administered during the initial10 min of R. Infarct size (IS) was determined by TTC staining. Myocardial systolic function was evaluated by the left ventricular developed pressure (LVDP) and the maximal rise velocity of LVP (+dP/dtmax) and diastolic function by assessed by the left ventricular end-diastolic pressure (LVEDP) and maximal decay velocity of LVP (-dP/dtmax). Other hearts (n = 3) were submitted to 60 min of P or 30 min of GI and 10 min of R, in the absence and in presence of LRE1. Lactate dehydrogenase (LDH) release was measured by spectrophotometry. In isolated mitochondria, the mitochondrial state was assessed through the Ca2+ retention capacity (CRC, Calcium Green 5 N). In cardiac homogenate, the ratio Bax/Bcl-2 the cytochrome C (cyt C) level as an apoptotic index and the content of PSer637-Drp1 (to estimate the mitochondrial fission) were also determined. Data were given as means ± SEM and analyzed using ANOVA followed by Turkey's test. A p b 0.05 was considered significant.ResultsLRE1 decreased IS [(16 ± 2% (n = 4) vs 32 ± 2% in IC (n = 6)] and improved post-ischemic recovery of myocardial systolic and diastolic function. At the end of R, LVDP was 74 ± 5% vs 18 ± 3% in IC and + dP/dtmax was 81 ± 5% vs 15 ± 3% in IC; LVEDP was 19 ± 4 vs. 55 ± 7 mmHg in IC and -dP/dtmax was 72 ± 7% vs 14 ± 3% in IC. LRE1 increased CRC (150 ± 21 vs 67 ± 14 nmol/mg protein) and reduced LDH release (1.56 ± 0.2 vs 3 ± 0.3 fold change). Hearts treated with LRE1 showed a decrease of Bax/Bcl-2 ratio (104 ± 5 vs 187 ± 5), and cyt C content (73 ± 5 vs 133 ± 6) and an increase of PSer637-Drp1 (124 ± 7 vs 75 ± 6) content.ConclusionThese data show that the inhibition of sAC with LRE1 reduces the myocardial and mitochondrial postischemic alterations and evidences the injurious role played by sAC in ischemia-reperfusion injury