Endogenous opioid peptides such as Met-enkephalin have diverse physiological actions, which include @entity551 and @entity1168 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. Anesthetized male @entity95 (2-3 kg) were instrumented for the measurement of blood pressure, heart rate, electrocardiogram and multiunit renal nerve activity (RNA). Intravenous administration of @entity1063 (15 micrograms/kg) or @entity2647 (50 micrograms/kg) produced a rapid increase in blood pressure followed by a reduction of RNA and heart rate. Met-enkephalin administered via the same route in doses of 1, 10, 100 and 1000 micrograms/kg initially decreased the RNA and subsequently reduced blood pressure. The above effects of Met-enkephalin were antagonized by @entity1510 (1 mg/kg i.v.) given 10 min before the peptide. @entity19244 (1.3 mg/kg i.v.), a quaternary derivative of @entity1510 , did not block the effects of Met-enkephalin under identical conditions. These results suggest that the @entity551 effect of Met-enkephalin is secondary to its effects on sympathetic outflow. Lack of @entity19244 action is due to its inability to cross the blood-brain barrier and is consistent with a centrally mediated action of Met-enkephalin.

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

@entity95 :: ('9986', 'Species') :: ['rabbits'] @entity19244 :: ('MESH:C041269', 'Chemical') :: ['naloxone methobromide', 'Naloxone methobromide'] @entity551 :: ('MESH:D007022', 'Disease') :: ['hypotensive', 'hypotension'] @entity1510 :: ('MESH:D009270', 'Chemical') :: ['naloxone'] @entity2647 :: ('MESH:D010656', 'Chemical') :: ['phenylephrine'] @entity1063 :: ('MESH:D009638', 'Chemical') :: ['norepinephrine'] @entity1168 :: ('MESH:D001919', 'Disease') :: ['bradycardia']
@entity95 :: (9986,Species) :: ['rabbits']
