Bradykinin causes endothelium-independent hyperpolarisation and neuromodulation by prostanoid synthesis in hamster mesenteric artery.
The mechanism of bradykinin-induced hyperpolarisation and purinergic neuromodulation was examined in the hamster superior mesenteric artery using intracellular microelectrode techniques. Bradykinin induced a concentration-dependent hyperpolarisation both in endothelium-intact and -denuded preparations. Indomethacin blocked this hyperpolarisation. Prostacyclin and iloprost also hyperpolarised the membrane of mesenteric artery, while prostaglandin E(2) did not evoke any membrane hyperpolarisation. The bradykinin-, prostacyclin- and iloprost-induced hyperpolarisation were inhibited by glibenclamide. Bradykinin also inhibited the amplitude of the purinergic excitatory junction potentials (e.j.p.s), both in endothelium-intact and -denuded preparations. Indomethacin blocked this inhibitory effect. Prostaglandin E(2) inhibited the e.j. p. in a concentration-dependent manner. Focally applied ATP-induced depolarisation was not modified by bradykinin or prostaglandin E(2.) These findings suggest that bradykinin via prostanoids production pre-synaptically, inhibit the amplitude of purinergic e.j.p., resulting inhibitory purinergic neuromodulation. In addition, bradykinin-released prostanoids elicits membrane hyperpolarisation of smooth muscle cells through opening of K(ATP) channels.
Thapaliya
S
S
Department of Pathogenetic Veterinary Science, The United Graduate School, Gifu University, 501-1193, 1-1 Yanagido, Gifu, Japan.
Matsuyama
H
H
Takewaki
T
T
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D006224:Cricetinae; D015232:Dinoprostone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D011464:Epoprostenol / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D016285:Iloprost / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D008638:Mesenteric Arteries / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008647:Mesocricetus; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects; D011453:Prostaglandins / Q000096:biosynthesis* / Q000494:pharmacology
D015221:Potassium Channels; D011453:Prostaglandins; D000255:Adenosine Triphosphate; D011464:Epoprostenol; D016285:Iloprost; D015232:Dinoprostone; D001920:Bradykinin; D005905:Glyburide; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin