Figure 1.

Concentration-dependent effects of mibefradil (n=6) and nifedipine (n=6) on spontaneous arteriolar tone (A) and KCl (60 mM)–induced vasoconstriction (B). Vessel diameters are plotted relative to the passive diameter at an intraluminal pressure of 70 mmHg. Basal indicates the level of spontaneous tone at 70 mmHg in the absence of Ca²⁺ channel antagonists (A); in (B) responses to 60 mM KCl in the absence of antagonist are shown to the left of the figure. (A) includes studies of the effect of increasing concentrations of mibefradil on myogenic tone in the presence of a maximally effective concentration of nifedipine (n=3). (B) includes a time control for KCl-induced vasoconstriction performed in the absence of Ca²⁺ channel antagonists (n=3). Results are presented as mean±s.e.mean.