FIGURE 7.

Effects of acute activation and inhibition of PKC on hormone-induced Ca²⁺ oscillations. The effects of PMA (1 nm) and BIM (5 μm) on phenylephrine (PE)-induced Ca²⁺ oscillations were examined in hepatocytes cultured for 1 h. Representative traces of PMA- (A) and BIM-treated (B) hepatocytes show either a decrease in oscillation frequency (top panel) or suppression of oscillations (bottom panel). The effect of drug treatment on phenylephrine-induced Ca²⁺ oscillation frequency (C) and Ca²⁺ spike width at half-peak height (D) are summarized. The frequencies of agonist-induced Ca²⁺ oscillations were calculated from 5-min periods in the absence or presence of the drugs. Ca²⁺ spike widths were calculated from the three oscillations prior to and after drug treatment. The drugs were present at least 1 min prior to carrying out the analysis. Data are mean ± S.E. from ≥15 cells from three independent experiments. **, p < 0.01; ***, p < 0.001; Student's t test. E, the effect of acute activation or inhibition of PKC and PKC-DR on total inositol phosphate production in response to 100 nm vasopressin (VP) stimulation for 15 min. Data are expressed as -fold increase over basal and are the mean ± S.E. from three independent experiments. *, p < 0.05; **, p < 0.01; analysis of variance.