Kunihiko Yokotani, Yasunobu Okuma and Yoshitsugu Osumi
Department of Pharmacology, Kochi Medical School, Nankoku, Kochi 783 -8505, Japan
Abstract: We characterized the voltage-activated Ca2+ channels involved in noradrenaline (NA) release from gastric sympathetic neurons using isolated, vascularly perfused rat stomach. The evoked NA release by electrical stimulation of periarterial nerves was abolished by calcium removal from the perfusion medium and by cadmium. omega-Conotoxin GVIA (N-type Ca2+-channel blocker) effectively and omega-conotoxin MVIIC (N/P/Q-type blocker) slightly inhibited the evoked NA, while omega-agatoxin IVA (P-type blocker) had no effect. These results suggest that omega-conotoxin GVIA and omega-conotoxin MVIIC-sensitive N-type Ca2+ channels are involved in NA release from the rat gastric sympathetic nerve terminals.
Keywords: Noradrenaline release, Rat stomach, N-type Ca2+ channel