THE FUNCTIONAL COMPLEX FORMED BY THE SODIUM/BICARBONATE COTRANSPORTER AND THE SOLUBLE ADENYLATE CYCLASE (sAC) MODULATES BASAL CARDIAC CONTRACTILITY.

ESPEJO M SOFIA; CIANCIO MC; ORLOWSKI A; AIELLO EA; DE GIUSTI VC

Buenos Aires

Congreso; ISHR-International Society for Heart Research; 2016

In addition to the adenylate cyclase (AC) embedded in the plasma membrane, another source of cyclic AMP (cAMP) was identified in the heart, the soluble AC (sAC). However, the physiological function of sAC is unknown. Moreover, the cardiac Na+/HCO3- cotransporter (NBC) promotes the cellular co-influx of HCO3- and Na+. Since sAC activity is mainly regulated by HCO3-, we aimed to investigate the potential impact on cAMP-dependent cardiac contractility of the relationship between the activity of NBC and sAC. Ventricular myocytes of 4 month old rat were loaded with Fura-2 or Fluo-3 in order to measure Ca2+ transient amplitude (CaT) by epifluorescence or Ca2+ sparks frequency (CaSF) by confocal microscopy, respectively. Sarcomere shortening as contractility index was measured simultaneously with epifluorescence. The NBC blocker S0859 (10µM) induced a negative inotropic effect (NIE) in the presence of HCO3- (Control: 19.1±3.2% vs. S0859: 14.6±2.6%; n=9, P