FIGURE 4.

Quantity of charge and secretion recruited by cAMP is sensitive to Ni²⁺. The T-type channel blocker Ni²⁺ (50 μM) has no effect on cAMP untreated cells, whereas it significantly reduces both Ca²⁺ currents and secretion after the long-term cAMP treatment. RCCs were pretreated with ω-toxins and nifedipine. (A) Representative traces for a cell depolarized at −20 mV. Left, cAMP-untreated cell; right, cAMP-treated cell. (B and C) Mean quantity of charge and mean secretory responses evaluated between −50 and +40 mV depolarizations. Ni²⁺ significantly reduced both the Ca²⁺ charge and the capacitance increases after cAMP treatment.