Figure 2.

Muscarinic cholinergic suppression of ISO-stimulated I_Ca-L is absent in eNOS^null ventricular myocytes. The effects of ISO and CCh on L-type calcium current (I_Ca-L) in ventricular myocytes from both WT and eNOS^null mice are shown. (A) CCh significantly inhibited ISO-stimulated I_Ca-L in WT myocytes. Current traces labeled a, b, and c were recorded under control conditions (a), during ISO infusion (10 nM) (b), and during CCh infusions (10 μM) in the continuous presence of ISO (c). Averaged data for 21 cells is illustrated in the bar graphs. (B) CCh had no significant effect on ISO-stimulated I_Ca-L in ventricular myocytes from eNOS^null mice. Current traces were recorded under control conditions (a), during ISO infusion (b), during CCh infusion in the continuous presence of ISO (c), and during infusion of the NO donor S-nitroso-acetyl-cysteine (SNAC) (100 μM) in the presence of ISO and CCh. Note that direct application of NO caused a significant inhibition in ISO-stimulated I_Ca-L (d).