Effects of dapiprazole on contractile responses of guinea pig isolated ileum.
The effects of dapiprazole, a relatively new alpha 1-adrenolytic agent, on contractile responses and on spontaneous mechanical activity were studied in guinea pig isolated ileum. Dapiprazole (10(-10) to 10(-4) M) produced a concentration-dependent inhibition of high K+ (80 mM) -induced contractions. These inhibitory effects were observed with dapiprazole added either before or after the induced contractions. The Ca2+-induced contractions of K+-depolarized ileum were also inhibited by dapiprazole. Dapiprazole inhibited in a non competitive manner the responses of the ileum to: carbachol, histamine, 5-hydroxytryptamine, pentagastrin, angiotensin II and cholecystokinin. In order to analize whether dapiprazole exerts an intracellular effect on Ca2+-store, skinned preparations were used. The results suggest that dapiprazole might inhibit Ca2+ entry through both voltage-and receptor-operated channels of the smooth muscle membrane.
D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010879:Piperazines; D011188:Potassium / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology*
D014150:Antipsychotic Agents; D010879:Piperazines; D014230:Triazoles; C035289:dapiprazole; D002122:Calcium Chloride; D011188:Potassium