Effect of Low Dosage of Naloxone on Clonidine- Induced Changes in Blood Pressure, Catecholamines, Renin, and Aldosterone in Essential Hypertension

Abstract

In spontaneously hypertensive rats opioid receptor blockade by naloxone reversed the antihypertensive effect of clonidine (Farsang and Kunos 1979, Farsang et al. 1980; Kunos et al. 1981; Baum and Becker 1982; Ramirez-Gonzales et al. 1983). A similar effect of naloxone was reported in normotensive rats by Bennet et al. (1982), whereas Farsang et al. (1980) found that naloxone was without effect. In man naloxone was without effect on the clonidine-induced fall in blood pressure in normotensive individuals (Watkins et al. 1980). In hypertensive man some investigators found that naloxone reduced the fall in blood pressure induced by clonidine (Farsang et al. 1982, 1984a, c), but other investigators were unable to confirm these results (Rogers and Cubeddu 1983; Pedrinelli et al. 1983; Mathias et al. 1985; Levin et al. 1986).