RESPONSES OF GOAT RUMINAL MUSCULATURE TO BRADYKININ AND SEROTONIN INVITRO AND INVIVO

  • 1 January 1980
    • journal article
    • research article
    • Vol. 41  (4) , 479-483
Abstract
Concentration-response curves obtained for contraction of goat rumen strips indicated that both bradykinin (BK) and serotonin (5-hydroxytryptamine creatinin sulfate; 5-HT) are potent agents. Sodium meclofenamate antagonized the smooth muscle-stimulating action of BK; the 5-HT blocking agents xylamidine and methysergide diminished the contractile effects of 5-HT. The antagonisms are noncompetitive in nature. In vivo, both BK and 5-HT caused a dose-dependent inhibition of the rumen contraction sequences. The BK was the more potent of the 2 compounds. This inhibition was probably due to an increase in ruminal smooth muscle tone, resulting in reflex inhibition of the normal cyclical contraction sequences. In conscious goats, BK induced tachycardia, whereas 5-HT produced only minor changes in heart rate. Treatment with sodium meclofenamate or phenylbutazone prevented the BK-induced inhibition of rumen motility. Treatment with the 5-HT blocking agents only partly reduced the 5-HT-induced effects.