title: Inhibition of spontaneous smooth muscle contractions in rat and rabbit intestine by blockers of the thromboxane A2 pathway.
abstract: The effect of inhibitors of the thromboxane A2 pathway on spontaneous contractions of intestinal smooth muscle preparations was studied. The thromboxane A2 antagonists Bay u3405, SK and F 88046 and KW-3635 concentration-dependently inhibited both the amplitude and the frequency of spontaneous contractions of the longitudinal muscle from the rat proximal colon. A concentration-dependent inhibition of the myogenic contractions was also observed with the thromboxane A2 synthase inhibitor U-51605, and with the combined cyclooxygenase/lipoxygenase inhibitor nordihydroguaiaretic acid, whereas indomethacin, a pure cyclooxygenase inhibitor, was ineffective. None of these inhibitors affected the contractile response evoked by the cholinergic agonist carbachol, excluding non-specific actions on intestinal motility. A similar response was observed for the rabbit jejunum, which, in contrast to the rat colon, exhibits more regular, high-frequency spontaneous contractions, which were inhibited by Bay u3405, SK and F 88046 and KW-3635 in a concentration-dependent manner, whereas the response to carbachol remained unaffected. These results suggest a role for thromboxane A2 in the generation and/or facilitation of spontaneous smooth muscle contractions in the gut.
authors.affiliation: Institut für Veterinär-Physiologie, Universität, Giessen, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Schultheiss
authors.forename: M
authors.initials: M
authors.lastname: Diener
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D001584:Benzoxepins / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D003106:Colon / Q000187:drug effects / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007421:Intestine, Small / Q000187:drug effects / Q000502:physiology*; D007537:Isometric Contraction / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors; D013449:Sulfonamides / Q000494:pharmacology; D013928:Thromboxane A2 / Q000037:antagonists & inhibitors*
chemical_list: D001562:Benzimidazoles; D001584:Benzoxepins; D002227:Carbazoles; D017482:Receptors, Thromboxane; C034339:SK&F 88046; D013449:Sulfonamides; D013928:Thromboxane A2; D009637:Masoprocol; D002217:Carbachol; C063119:ramatroban; C065729:KW 3635; D007213:Indomethacin