G_i, but not cSrc, mediates P4’s inhibition of the rapid actions of BPA in female rat ventricular myocytes. (a) Representative immunoblot and quantification of PLN17 phosphorylation and total PLN under control, BPA, and BPA in the presence of P4, P4 + 1 μM PP2, or PP2. (b) Representative recordings and percentages of myocytes with triggered activities under various treatments (n = 32 to 47 myocytes from four hearts). (c) Representative immunoblot and quantification of PLN17 phosphorylation and total PLN under control, BPA, and BPA in presence of P4, P4 + 200 ng/mL PTX, or PTX. (d) Representative recordings and percentages of myocytes with triggered activities under various treatments (n = 30 to 42 myocytes from four hearts). BPA and P4 = 1 nM for all experiments. *P < 0.05; **P < 0.01; ^#P > 0.1 versus control; ^†P < 0.01 (χ² test). NS, not significant.