Cardiovascular response to injections of enkephalin in the pressor area of the ventrolateral medulla

Susan Punnen, R. Willette, A. J. Krieger, H. N. Sapru

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

The cardiovascular effects of the injection of an enkephalin analogue, [d-ala2-met5]enkephalinamide (DAME) into the pressor area of the rostral ventrolateral medulla were studied in urethane-anesthetized and decerebrate rats. The excitatory amino acid l-glutamate was used to identify the ventrolateral medulla. The pressor responses to l-glutamate were elicited from an area that included the nucleus reticularis gigantocellularis, the medial aspect of the nucleus reticularis parvocellularis and the dorsal portion of the nucleus reticularis lateralis. Injection (0.1μl volume) of DAME (2.5-500.0 ng/site) into the ventrolateral medulla elicited a dose-related decrease in arterial blood pressure and heart rate and attenuated the carotid occlusion response (COR). Control injections (0.1-0.2 μl vol) of saline into the same area failed to produce any response. The specificity of this opiate response was tested with naloxone HC1, an opiate antagonist, which prevented, as well as reversed, the action of DAME both by intravenous (i.v.) administration and by injection into the ventrolateral medulla. It was concluded that the ventrolateral medulla plays a role in the generation of vasomotor tone and that stimulation of opiate receptors in this area by an enkephalin analogue produced hypotension, bradycardia and modification of cardiovascular reflexes.

Original languageEnglish (US)
Pages (from-to)939-946
Number of pages8
JournalNeuropharmacology
Volume23
Issue number8
DOIs
StatePublished - Aug 1984

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Cellular and Molecular Neuroscience

Keywords

  • bradycardia
  • carotid occlusion
  • enkephalin
  • hypotension
  • naloxone
  • opiate receptors
  • vasopressor neurons
  • ventrolateral medulla

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