Cardioprotective effects of n-methylacetazolamide mediated by inhibition of l-type Ca2+ current

GONZÁLEZ ARBELÁEZ LF; DIAZ RG; CIOCCI PARDO, A; IBAÑEZ A; MOSCA SM; DIAZ L; AIELLO A

Rosario

Congreso; Reunión anual Sociedad Argentina de Fisiología SAFIS; 2019

Our objective was to examine the effects of N-methylacetazolamide (NMA), a non-carbonic anhydrase inhibitor, on themyocardial post-ischemic alterations. For it, isolated perfused rat hearts were assigned to the following groups: 1) Nonischemic control (NIC):110 min of perfusion and 2) Ischemic control (IC): 30 min of global ischemia and 60 min of reperfusion(R). Both groups were repeated in presence of NMA (5 µM), which was administered during the first 10 min of R. Infarct size(IS) was measured by TTC staining. Developed pressure (LVDP) and end-diastolic pressure (LVEDP) of the left ventricle wereused to assess systolic and diastolic function, respectively. The content of phosphorylated forms of Akt and PKCɛ were alsoevaluated. The changes of pHi in papillary muscle by immunofluorescence were determined. In isolated ventricular myocytesthe L-type Ca2+ current (ICa) with the whole-cell configuration of patch-clamp technique and intracellular Ca2+ transients(estimated by the Fura 2AM fluorescence ratio) simultaneously monitored with cell shortening were measured. In NIC groupthe NMA decreased the contractility a 20 % vs 3 % in non-treated hearts. In IC group, NMA decreased IS (22 ± 2 % vs 32 ± 2%, p < 0.05) and improved the post-ischemic recovery of myocardial function. At the end of R, LVDP was 54 ± 7 % vs 18 ± 3 %and LVEDP was 23 ± 8 vs. 55 ± 7 mmHg (p < 0.05). The P-Akt and P-PKCɛ levels increased 20 % in hearts treated with NMAcompared to IC non-treated hearts. In papillary muscle, NMA did not modified the pHi recovery from sustained intracellularacidosis. Peak I(Ca) density recorded at 0 mV was smaller in myocytes treated with NMA than non-treated (-2.01 ± 0.26pA/pF vs -2.41 ± 0.27 pA/pF, p < 0.05). Ca2+ transient amplitude and cell shortening, explored at 1 mM extracellular Ca2+,decreased but not significantly after NMA treatment.These data demonstrated that NMA cardioprotects the myocardium against ischemi-reperfusion injury. The diminution of Ltype Ca2+ current appears as the responsible mechanism, participating Akt and PKCɛ-dependent pathways