Figure 5

A. Effects of protein kinase C inhibitor (PKCi) chelerythrine on inotropic responses (developed pressure) of perfusate calcium 1.5 to 2.5 mM (left), 2.5 to 3.5 mM (middle), and dobutamine (right). B. Effects of PKCi with perfusate calcium 2.5 to 3.5 mM (left) on peak systolic intracellular calcium, and basal diastolic calcium (right). Baseline controls values (perfusate calcium 1.5, 2.0 or 2.5 mM) for these experiments include those experiments with addition of chelerythrine to the higher perfusate calcium or dobutamine after control measurements, combined also with those experiments without chelerythrine. ^* p < 0.05, and ^** p < 0.005.