Effect of an homologous series of aliphatic alcohols on neuronal and smooth muscle voltage-dependent Ca 2+ channels

Abstract

The acute inhibitory actions of alcohol on K +-stimulated 45Ca 2+ uptake into synaptosomes shows regional variation in sensitivity throughout the brain, suggesting the possibility of a selective action on a specific Ca 2+ channel subtype. This was examined by comparing the effects of a homologous series of aliphatic alcohols on synaptosomal Ca 2+ channels with their actions on K +-stimulated Ca 2+ channels in guinea-pig intestinal longitudinal muscle, which have been demonstrated to be of the L-type. K +-stimulated contraction of and [ 3H]nitrendipine binding to smooth muscle were both inhibited by the alcohols at similar concentrations, with the potency increasing with chain length. In synaptosomes, however, K +-stimulated 45Ca 2+ uptake was 5–30 times more sensitive to the inhibitory actions of alcohol than were [ 3H]nitrendipine and [ 125I]ω-conotoxin binding. These observations suggest that K +-stimulated 45Ca 2+ uptake is mediated by a non-L non-N type channel which is more sensitive to the acute effects of alcohols. This is supported by the observation that K +-stimulated 45Ca 2+ uptake which is insensitive to L-and N-channel antagonists was inhibited by funnel web spider venom.