Effects of naloxone on glucose level in the hepatic venous plasma in the rat.

1. The effect of opioid receptor blockade by naloxone in vivo on hepatic venous plasma glucose concentration in rats was investigated. 2. The plasma glucose levels in naloxone-injected animals (10 mg/kg) were higher than in the control animals (P less than 0.05). 3. At the lower dose of naloxone (2 mg/kg) the resulting plasma glucose concentration did not differ significantly from control (P greater than 0.1). 4. It is concluded that endogenous opioids may moderate the regulation of basal glucose levels in the rat.