Figure 6. Suppression the Ca²⁺ channel by inhibition of haem oxygenase.

A, brief exposures to the haem oxygenase inhibitor ZnPP in concentrations of 10 and 100 nm cause rapid, reversible, dose-dependent suppression of I_Ca. B, effect of 10 nm ZnCl₂ or 100 nm ZnPP on I_Ca. Insets in panels A and B show traces of I_Ca measured at the indicated times (a, b and c). C and D, normalized I–V relations of I_Ba measured in control cells (Control, open circles) and in cells exposed to 100 nm ZnPP (C,filled triangles) that was applied either in the external solution (C) or via the patch pipette by 9 min of dialysis (D). All experiments were performed on rat ventricular cardiomyocytes under normoxic and non-phosphorylating conditions.