Sympathoinhibition by rilmenidine in conscious rabbits: involvement of alpha 2-adrenoceptors.

摘要: Cardiovascular and sympathetic nervous system effects of the mixed alpha 2-adrenoceptor imidazoline receptor agonist rilmenidine were studied in conscious rabbits chronically instrumented for recording firing rate renal fibers. Separate experiments carried out on pithed with electrically stimulated (2 Hz) outflow. Drugs administered intravenously a cumulative manner. In rabbits, 0.1, 0.3 1.0 mg kg-1 dose-dependently lowered blood pressure, nerve activity, heart plasma concentration noradrenaline adrenaline. The effect pressure catecholamines was maximal after whereas activity decreased further kg-1. Yohimbine 0.1 0.5 kg-1, when injected subsequently, attenuated at higher dose abolished all rilmenidine. also antagonized by antagonist 2-(2,3-dihydro-2-methoxy-1,4-benzodioxin-2-yl)-4,5-dihydro-1H-imid azole HCl (RX821002; kg-1). did not attenuate or only slightly decrease produced infusion vasopressin. electrically-stimulated outflow, yohimbine submaximally maximally increased concentration. show direct measurement that causes sympathoinhibition presumably through central sites action.(ABSTRACT TRUNCATED AT 250 WORDS)