Cardiovascular effects of substance P receptor stimulation in the ventrolateral medullary pressor and depressor areas

Raymond W. Urbanski, Jaya Murugaian, Abbott J. Krieger, Hreday N. Sapru

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Abstract

The pressor (VLPA) and the depressor (VLDA) areas in the ventrolateral medulla were identified with the microinjection of l-glutamate (1.77 nmol/site) in artificially ventilated urethane-anesthetized male Wistar rats. Bilateral microinjection of a stable substance P (SP) agonist [pGlu5, MePhe8, Sar9]-SP(5-11)], abbeviated as DiMe, into the VLPA (6-600 pmol/site) produced a dose-dependent increase in blood pressure (BP). The effects on heart rate (HR) were variable. Intravenous pretreatment with a ganglionic blocker chlorisondamine (3.0 mg/kg, i.v.), but not with a vasopressin antagonist, blocked these responses. Similar microinjection of DiMe (6-600 pmol/site) into the VLDA produced a dose-dependent decrease in HR but had no effect on BP levels. The DiMe-induced bradycardic response elicited from the VLDA was blocked by i.v. pretreatment with atropine methylbromide (0.5 mg/kg, i.v.). These findings indicate that there are SP receptors localized on sympathoexcitatory neurons in the VLPA and that SP may be an excitatory neurotransmitter in this area. In the VLDA, the SP receptors appear to be localized on a subpopulation of neurons that affect vagal, but not sympathetic, outflow to the heart.

Original languageEnglish (US)
Pages (from-to)383-389
Number of pages7
JournalBrain research
Volume491
Issue number2
DOIs
StatePublished - Jul 10 1989

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All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Keywords

  • Blood pressure
  • Depressor area
  • Heart rate
  • Pressor area
  • Substance P
  • Wistar rat

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