Angiotensin II-induced increase of T-type Ca2+ current and decrease of L-type Ca2+ current in heart cells

The effect of angiotensin II (Ang II) on the T- and L-type calcium currents (I-Ca) in single ventricular heart cells of 18-week-old fetal human and 10-day-old chick embryos was studied using the whole-cell voltage clamp technique. Our results showed that in both, human and chick cardiomyocytes, Ang II (10(-7) M) increased the T-type calcium current and decreased the L-type I-Ca. The effect of Ang II on both types of currents was blocked by the AT(1) peptidic antagonist, [Sar(1), Ala(8)] Ang II (2 x 10(-7) M). Protein kinase C activator, phorbol 12,13-dibutyrate, mimicked the effect of Ang II on the T- and L-type calcium currents. These results demonstrate that in fetal human and chick embryo cardiomyocytes Ang II affects the T- and L-type Ca2+ currents differently, and this effect seems to be mediated by the PKC pathway. (c) 2005 Elsevier Inc. All rights reserved.