Effects of [Met5]enkephalin on regional blood flow and vascular resistance in rabbits.

Methionine enkephalin [( Met5]enkephalin) has different cardiovascular effects, depending on species and routes of peptide administration. In anesthetized animals [Met5]enkephalin decreases blood pressure and heart rate. The site(s) and the mechanism of the hypotensive effects of the peptide are not known.

Suppression of renal nerve activity by methionine enkephalin in anesthetized rabbits.

Endogenous opioid peptides such as Met-enkephalin have diverse physiological actions, which include hypotension and bradycardia in anesthetized animals. The exact sites, the mechanism and the physiological significance of the cardiodepressant effects are not known. The main purpose of this work was to correlate the effect of Met-enkephalin on the rate of sympathetic nerve discharge with its cardiodepressant actions.

Reduction by phentolamine of the hypotensive effect of methionine enkephalin in anaesthetized rabbits.

In intact rabbits anaesthetized with pentobarbitone, methionine enkephalin (Met enkephalin, 1-1,000 micrograms kg-1 i.v.) produced a dose-dependent bradycardia and hypotension.