Figure 4.

NA inhibited high-voltage-activated Ca²⁺ channels in MCs via a G-protein. (A) Individual current records before, during, and after bath application of NA (10 µM). Ba²⁺ was used as the charge carrier. Calibration: 50 msec, 0.5 nA. (B) Current-voltage relationships taken before and during NA (10 µM, left) or clonidine (Clo, 5 µM, right) and after Cd²⁺(200 µM). (C) Individual current records before and during the application of Clo (5 µM) in slices treated with vehicle or PTX. Calibration: 50 msec, 0.5 nA. (D) Pooled data showing that the G_i/o-protein inhibitor PTX reverses the effect of Clo. (**) P < 0.01 versus the predrug control.