Two-fold effect of Angiotensin II on voltage-dependent calcium currents in rat retinal ganglion cells

Angiotensin II (AngII) is one of the most important vasoconstrictive hormones but is also known to act as a neuromodulator in the central nervous system (CNS). Recently, AngII-containing neurons have been identified in the inner nuclear layer and the ganglion cell layer of the retina of various vertebrate species. The present study was undertaken to investigate the physiological effect of AngII on voltage-activated ion channels in retinal ganglion cells of the rat, Ion currents were recorded in freshly dissociated cells in the whole-cell configuration of the patch-clamp technique. AngII concentrations of 1 to 100 microM had no effect on sodium currents but modulated the influx through high voltage-activated (HVA) calcium channels in a 2-fold manner. AngII (100 microM) increased the HVA-calcium current by 15 to 65% in 41% of the cells, whereas a current reduction of 18 to 69% was observed in 59% of the cells. AngII effects were reversible within a few seconds of reperfusion with bath solution. Calcium-current kinetics and current-voltage relations remained unaffected.