Figure 4.

Effects of various Ca²⁺ channel blockers shown as % inhibition of the Ca²⁺ response to 75 mM K⁺. The L-type Ca²⁺ channel blocker nifedipine (1 μM) inhibited 40% of the response, whereas there was no effect of a highly specific L-type blocker, the neurotoxin calciseptine (500 nM). Highly specific neurotoxin blockers of P/Q-type (ω-agatoxin IVA, 100 nM), N-type (ω-conotoxin MVIIA, 500 nM), or R-type Ca²⁺ channels (SNX-482, 100 nM) did not inhibit the response to high K⁺. There was a minor increase of the Ca²⁺ response in the presence of ω-agatoxin IVA. The number of arterioles is within parenthesis. ^*P<0.05; t-test vs untreated control experiments.