Fig. 3.

Chronic quinpirole treatment in vitro induces a long-lasting suppression of total Ca²⁺ channel currents in melanotropes.A, Currents recorded in the presence of 1 μm Bay K 8644 using 100 msec depolarizations from a holding potential of −50 mV to several potentials from a representative control cell. B, Plot of peak currents (normalized to membrane capacitance) recorded during 100 msec depolarizations to various potentials versus voltage in melanotropes cultured in the absence or presence of quinpirole for 5–10 d. Data inA and B were obtained from melanotropes dissociated by trypsin–viokase digestion (see Materials and Methods).