Pindolol increases plasma norepinephrine concentration by stimulation of β2-adrenoceptors in conscious spontaneously hypertensive rats

T. Kent Keeton

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The β-adrenoceptor antagonist pindolol [10-1,000 μg/kg subcutaneously (s.c.)] caused dose-related decreases in mean arterial pressure (MAP) and increased heart rate (HR) in conscious spontaneously hypertensive rats (SHR). The lowest dose of pindolol (10 μg/kg) decreased MAP by 25 mm Hg (- 16%) without affecting plasma norepinephrine (NE) or plasma renin concentration (PRC). However, higher doses of pindolol elicited dose-related increases in plasma NE concentration and PRC. Plasma epinephrine concentration was not altered by pindolol. The selective β2-adrenoceptor antagonist ICI 118,551 (3 mg/kg, s.c.) prevented the tachycardia but not the increase in PRC caused by 100 μg/kg pindolol. Treatment with ICI 118,551 completely eliminated the 45% increase in plasma NE elicited by 100 μg/kg of pindolol even though the decrease in MAP caused by this dose of pindolol was the same in the presence (-33 mm Hg) and absence (-34 mm Hg) of β2-adrenoceptor blockade. These results indicate that the vasodepressor action of pindolol in SHR does not result from an agonistic effect at postjunctional β2-adrenoceptors in the vasculature. In addition, the increases in plasma NE concentration produced by pindolol result from stimulation of β2-adrenoceptors. These β2-adrenoceptors may be located prejunctionally on sympathetic neurons.

Original languageEnglish (US)
Pages (from-to)354-359
Number of pages6
JournalJournal of Cardiovascular Pharmacology
Volume16
Issue number3
DOIs
StatePublished - Sep 1990
Externally publishedYes

Keywords

  • ICI 118,551
  • Pindolol
  • Plasma norepinephrine concentration
  • Plasma renin concentration
  • Spontaneously hypertensive rat
  • β-adrenoceptors

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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