Figure 3. The potentiating effect of NO donors on the Iso-stimulated I_Ca,L is cGMP-independent in rat ventricular myocytes.

A, a myocyte was first exposed to control solutions. Superfusion of the myocyte with 0.2 nm Iso alone or in combination with SNAP (1 nm or 1 μm) or 1H-[1, 2, 4]oxadiazolo[4, 3-a]quinoxaline-1-one (ODQ) (10 μm) is indicated by the lines. Traces were recorded at the times indicated by the corresponding letters on the main graph (a-h). The dotted line indicates the zero-current level. B, mean stimulatory effects of Iso (0.1 and 0.2 nm) on I_Ca,L, in the presence (filled bars) and in the absence of 10 μm ODQ (open bars), with or without SNAP (1 nm or 1 μm), as indicated. The amplitude of I_Ca,L in the presence of agonists was normalised to the amplitude of the basal I_Ca,L in the absence of agonists. Bars are the means and vertical lines are the s.e.m. of the number of experiments indicated near the bars. Significant differences from the Iso level: *P≤ 0.05; ***P≤ 0.005.