Selective blockade of the responses of reticulo-ruminal muscle to 5-HT in sheep.
The effects of intravenous administration of 5-HT on the patterns of reticulo-rumen contractions were studied in conscious sheep. Contractions were measured by strain gauges applied to the external wall of the reticulum and the ventral and/or dorsal sac of the rumen. The responses to 5-HT comprised (i) a short-lived contraction followed by (ii) a sustained increase in muscle tone and (iii) a concomitant inhibition of the extrinsic reticulo-rumen contractions. The corresponding blockades produced by (i) atropine, (ii) 5-HT antagonists and (iii) chemical sympathectomy suggest involvement of a peripheral cholinergic mechanism in the initial contractile response and a central adrenergic mechanism in the reflex inhibition of extrinsic reticulo-rumen contractions.
D000818:Animals; D005260:Female; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D012159:Reticulum / Q000187:drug effects*; D012417:Rumen / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D012756:Sheep
D012701:Serotonin