Desensitization of PGE2 and PGI2 induced contractions in different smooth muscles of guinea-pig unmasking relaxing properties of prostanoids.
Prostaglandin E2 (PGE2) and 16,16-dimethyl PGE2 (16,16-dm PGE2) caused contraction of guinea-pig taenia caeci, contraction and at higher concentrations relaxation of trachea and relaxation of ureter smooth muscle. The prostacyclin derivative iloprost induced contraction of taenia caecum, while it was inactive in the other preparations. After pretreatment of the smooth muscles with 16,16-dm PGE2, stimulation of the PGE2 receptors in taenia caeci and trachea and of PGI2 receptors in taenia caeci caused relaxation. The results indicate that the prostanoid receptor mediating contraction is selectively vulnerable for desensitization in contrast with the receptor mediating smooth muscle relaxation.
D015064:16,16-Dimethylprostaglandin E2 / Q000494:pharmacology; D000818:Animals; D002432:Cecum / Q000187:drug effects; D015232:Dinoprostone; D011464:Epoprostenol / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D016285:Iloprost; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D011453:Prostaglandins / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects; D014513:Ureter / Q000187:drug effects
D011453:Prostaglandins; D011458:Prostaglandins E; D011464:Epoprostenol; D016285:Iloprost; D015232:Dinoprostone; D015064:16,16-Dimethylprostaglandin E2