title: Vasodilator actions of TRK-100, a new prostaglandin I2 analogue.
abstract: TRK-100, a stable analogue of prostaglandin I2 (PGI2), relaxed isolated arteries of the dog precontracted with PGF2 alpha or K+; the relaxation was in the order of mesenteric and renal greater than coronary and femoral greater than basilar and middle cerebral arteries. The relaxation by TRK-100 was not affected by treatment with atropine, propranolol, cimetidine, aminophylline, and indomethacin, but was suppressed by diphloretin phosphate, a prostaglandin antagonist. Treatment with TRK-100 attenuated the contraction induced by PGF2 alpha and Ca2+ in mesenteric and basilar arteries previously exposed to Ca2+-free medium, but did not significantly alter the contractile response to Ca2+ in the arteries exposed to Ca2+-free medium and depolarized by excess K+. TRK-100 and nitroglycerin relaxed isolated mesenteric arteries to a similar extent; however, when continuously infused into mesenteric arteries in anaesthetized dogs, TRK-100 produced greater vasodilatation than nitroglycerin. It is concluded that TRK-100 relaxes dog mesenteric and renal arteries more than cerebral arteries; the relaxation appears to derive from interference with the release of Ca2+ from intracellular stores and with the transmembrane Ca2+ influx through a receptor-operated channel. TRK-100 may vasodilate large and small mesenteric arteries and resistance vessels to a similar extent, whereas nitroglycerin preferentially dilates the large artery.
mesh_terms: D000818:Animals; D001488:Basilar Artery / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D015237:Dinoprost; D004285:Dogs; D011464:Epoprostenol / Q000494:pharmacology* / Q000031:analogs & derivatives; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D005996:Nitroglycerin / Q000494:pharmacology; D011121:Polyphloretin Phosphate / Q000494:pharmacology; D011460:Prostaglandins F / Q000494:pharmacology; D013152:Splanchnic Circulation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D011460:Prostaglandins F; D014665:Vasodilator Agents; C048081:beraprost; C013509:diphloretin phosphate; D011121:Polyphloretin Phosphate; D015237:Dinoprost; D011464:Epoprostenol; D005996:Nitroglycerin; D002118:Calcium