Figure 4. Accentuated antagonism of ACh on ICa in the presence of intracellular Methylene Blue.
A, the cell was internally perfused with a pipette solution containing 20 μM MBlue throughout the entire experiment, as indicated by the bar. After superfusion of the cell with control solution, the cell was exposed to 5-HT (10 nM) and subsequently to the same solution containing 1 μM ACh during the periods indicated by the upper bars. B, comparison of the effects of 5-HT and ACh in the absence (Control) and presence of 20 μM intracellular MBlue (means ±s.e.m.; number of experiments indicated above the vertical columns). n.s., not significant.