Relaxant effects of sulfonylureas on induced contractions of rat uterine smooth muscle: role of intracellular calcium.
We have investigated the action of tolbutamide and glibenclamide in a Ca-dependent process: the contractile activity of smooth muscle (uterus). The results obtained show that sulfonylureas are capable of relaxing contractions of rat uterus induced by various agents: oxytocin, acetylcholine and KCl in a medium with Ca2+. The capacity of sulfonylureas to also relax oxytocin-induced Ca-free contraction indicates the possibility that the action of these drugs could be due, above all, to a decrease in the intracellular free calcium level. Since maintained contraction induced by oxytocin in a Ca-free solution could be repeated after making a relaxation dose-response curve to sulfonylurea, the most likely mechanism of sulfonylurea-induced uterine relaxation is not an increase in the efflux of Ca but an increase in the Ca-uptake by intracellular organelles.
Villar
A
A
D'Ocon
M P
MP
Anselmi
E
E
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000187:drug effects; D010121:Oxytocin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D014044:Tolbutamide / Q000494:pharmacology; D014590:Uterine Contraction / Q000187:drug effects*
D013453:Sulfonylurea Compounds; D010121:Oxytocin; D014044:Tolbutamide; D000109:Acetylcholine; D005905:Glyburide; D002118:Calcium