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

ESPEJO MS; CIANCIO MC; ORLOWSKI A; DE GIUSTI VC; AIELLO EA

Baltimore

Congreso; Annual Congress of Biophysical Society; 2015

Biophysical Society

In addition to the adenylate cyclase (AC) associated to the plasma membrane, a new source of cyclic AMP (cAMP) was identified, the soluble AC (sAC). However, the physiological function of sAC in the heart is unknown. The cardiac Na+/HCO3- cotransporter (NBC) promotes the cellular co-influx of HCO3- and Na+. Since sAC is a HCO3--dependent enzyme, we aimed to investigate the potential impact on cAMP-dependent cardiac contractility of the relationship between the activity of NBC and sAC. Rat ventricular myocytes 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 (10M) 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