Effects of bepridil hydrochloride on calcium-induced responses in guinea pig Langendorff heart.

A spontaneously beating guinea pig Langendorff heart preparation was used to evaluate and compare the effects of bepridil hydrochloride (BP) and other Ca blockers. Cardiac contractile force was measured in isolated hearts perfused at constant pressure with nonrecirculating Krebs-Henseleit physiological salt solution (PSS). The calcium-induced inotropic response was assessed by measuring contractile force during stepwise increases in PSS Ca concentration. The results suggest that the effects of BP on cardiac muscle are different from those of the other Ca blockers tested and may involve multiple cellular mechanisms of action.