Figure 4.

The calcium channel blockers nifedipine and cadmium have little effect on contractions to exogenous application of a P2X receptor agonist (a) Typical responses from a large artery showing the effect of nifedipine (1 μM) and CdCl₂ (300 μM) on responses to an EC₅₀ concentration of α,β-meATP. (b) Histogram shows mean data±s.e.mean (n=4 – 6 arteries from 3 – 4 animals) for small, medium and large arteries. (c) Traces showing nifedipine resistance of control responses to 60 mM KCl in small arteries. The component of constriction resistant to nifedipine (1 μM) is abolished by CdCl₂ (300 μM). Periods of drug application are indicated by bar.