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 × 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 Ca 2+ currents differently, and this effect seems to be mediated by the PKC pathway.