Analgesic effects of intrathecally-applied alpha 2-adrenoceptor agonists in conscious, unrestrained sheep.
Intrathecal injections of small volumes of the alpha 2-adrenoceptor agonists, xylazine and clonidine, into the cervical region of the spinal cord of conscious unrestrained sheep produced a dose-dependent analgesia of the forelimbs as measured using a mechanical pressure device. Intravenous injection of the alpha 2-adrenoceptor antagonist, idazoxan completely abolished the analgesic effects of the intrathecally applied alpha 2-adrenoceptor agonists. Subsequent studies using [3H] clonidine injected at a similar dose and volume via the intrathecal catheters, indicated that the volume of drug used, 100 microliter, gave a localisation of the drug limited to about five vertebral segments around the catheter tip.
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000700:Analgesics / Q000008:administration & dosage; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D019329:Idazoxan; D007278:Injections, Spinal; D012756:Sheep; D013997:Time Factors; D014991:Xylazine / Q000037:antagonists & inhibitors / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000700:Analgesics; D004146:Dioxanes; D014991:Xylazine; D003000:Clonidine; D019329:Idazoxan