GENDER DIFFERENCE IN THE BASAL INTRACELLULAR CA2-CELLS( CONCENTRATIONIN RAT VALVULAR ENDOTHELIAL)

Intracellular Ca2+ concentration ([Ca2+](i)) was measured by Fura 2/AM fluorescence imaging microscopy in freshly isolated valvular endothel ial cells taken from female and male rats. The basal level of [Ca2+](i ) was significantly elevated in female valvular endothelial cells when compared to males (P < 0.05). Inhibition of the sarco-endoplasmic ret iculum Ca2+-ATPase with cyclopiazonic acid (CPA, 10 mu M) caused a gre ater increase in the [Ca2+](i) in female than male endothelial cells. Removal of extracellular Ca2+ returned the [Ca2+](i) to the basal leve l. The rate of [Ca2+](i) decline was significantly slower in female en dothelial cells compared to males. There were no differences in the un stimulated rate of Mn2+ quenching between two groups. These results de monstrate that estrogen affects NOS at least in part, by an alteration in Ca2+ homeostasis in endothelial cells. (C) 1998 Academic Press.