oxymorphone and Hypertension

The role of endogenous peripheral opioid mechanisms in renal function was evaluated in normotensive and hypertensive rats. Intravenous naloxone methylbromide, a quaternary opioid antagonist with limited ability to cross the blood-brain barrier, was used to inhibit endogenous peripheral opioid mechanisms. In normotensive rats, the opioid antagonist impaired the normal renal adaptive response to dietary sodium restriction. In spontaneously hypertensive rats, the opioid antagonist did not affect the renal functional responses to acute environmental stress. These data indicate that, depending on the nature of the intervention, a role for endogenous peripheral opioid mechanisms in the renal function responses may be identified.

Topics: Acute Disease; Animals; Endorphins; Hypertension; Kidney; Male; Natriuresis; Oxymorphone; Rats; Rats, Inbred SHR; Rats, Sprague-Dawley; Sodium; Stress, Physiological; Sympathetic Nervous System

Pain sensitivity in Spontaneously Hypertensive Rats (SHR) and normotensive Wistar-Kyoto controls (WKY) as well as in experimentally hypertensive Wistar rats has been studied. Results indicate a diminished responsiveness to noxious stimuli in SHR when compared with WKY. This hypoalgesia is altered neither by chronic treatment with the antihypertensive drugs hydralazine and captopril nor by the peripherally acting opiate antagonist N-methylnaloxone. Induction of renal and DOCA-salt hypertension in Wistar rats and Wistar-Kyoto rats did not affect nociceptive responsiveness. It is concluded that opiate receptors within the central nervous system are involved in the hypoalgesia in SHR and that pain perception appears to be dissociated from blood pressure regulation in the rat strains used.

Topics: Animals; Antihypertensive Agents; Desoxycorticosterone; Hypertension; Hypertension, Renal; Male; Nociceptors; Oxymorphone; Rats; Rats, Inbred Strains; Receptors, Opioid