Blockade of alpha 2-adrenoceptors protects the vagal baroreflex system from transient global cerebral ischemia in dogs.
Ifenprodil, phentolamine, yohimbine or idazoxan, 1 mg/kg i.v., administered 5 min prior to 5-min global cerebral ischemia, completely prevented the post-ischemic dysfunction of the vagal baroreflex in anesthetized dogs. Idazoxan, 0.1 mg/kg i.v., was cerebroprotective against mild ischemia, but ineffective against severe ischemia. The post-ischemic administration of idazoxan, 1 mg/kg i.v., failed to restore the damaged vagal baroreflex. These results suggest that blockade of alpha 2-adrenoceptors during ischemia and the early reperfusion period may protect the vagal component of baroreflex from cerebral ischemia.
Kurihara
J
J
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
Tamaoki
S
S
Kato
H
H
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D017704:Baroreflex / Q000187:drug effects*; D004146:Dioxanes / Q000494:pharmacology; D004285:Dogs; D005260:Female; D019329:Idazoxan; D002546:Ischemic Attack, Transient / Q000517:prevention & control*; D008297:Male; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology*
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D018340:Receptors, Adrenergic, alpha-1; D019329:Idazoxan