Trachealis responses induced by vincamine and vinpocetine; inhibition by indomethacin and Ca2+ dependence.
Vincamine in low concentrations induced a sustained contraction of the isolated guinea pig trachealis with long latency and slow onset and, in high concentrations, it induced relaxation which was potentiated in the precontracted trachealis. Vinpocetine had actions similar to those of vincamine on trachealis, however its relaxant effect was more pronounced. The vincamine-induced trachealis contraction was not changed by substance P desensitization, was reduced by tetrodotoxin, nifedipine and low Ca2+ high Mg2+ solution and increased in nominally Ca2+-free solution. The vincamine-induced relaxation of precontracted trachealis was increased by guanethidine and was not affected by propranolol, high Mg2+-low Ca2+ solution and tetrodotoxin. Vincamine- and vinpocetine-induced trachealis contraction as well as vinpocetine-induced relaxation at basal tension were abolished by indomethacin. Vincamine in a low concentration shifted to the left the concentration-effect curve for CaCl2 in the K+-depolarized trachealis, and shifted it to the right at a high concentration. Our results indicate that the contractile and relaxant actions of vincamine and vinpocetine on the guinea pig trachealis may be due to the generation of prostaglandins and to changes in the membrane Ca2+ fluxes and/or the intracellular Ca2+ distribution.
Machová
J
J
Institute of Experimental Pharmacology, Centre of Physiological Sciences, Slovak Academy of Sciences, Bratislava, Czechoslovakia.
Bauer
V
V
Bilcíková
L
L
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology*; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects; D014665:Vasodilator Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014748:Vinca Alkaloids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014749:Vincamine / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D014665:Vasodilator Agents; D014748:Vinca Alkaloids; C013983:vinpocetine; D006632:Histamine; D014749:Vincamine; D000109:Acetylcholine; D002118:Calcium; D007213:Indomethacin