Myocardial beta-adrenergic receptors in the stroke-prone spontaneously hypertensive rat

A. Mukherjee, R. M. Graham, Arthur I Sagalowsky, W. Pettinger, K. E. McCoy

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

In view of the severity of the hypertension in the stroke-prone spontaneously hypertensive rats (sp-SHR), myocardial beta-adrenergic receptors were investigated by the binding of (−)[3H]-dihydroalprenolol (DHA) to membranes from sp-SHR (9-week-old males, Okamoto-Aoki strain) and age-matched and sex-matched normotensive Wistar-Kyoto rats. Scatchard analysis showed no significant differences in binding parameters between sp-SHR and normal rats. Myocardial membranes from sp-SHR bound 31.8 ± 2.3 fmol DNA per mg protein with a dissociation constant of 3.8 ± 0.9 nm, whereas membranes from normal rats bound 33.4 ± 2.9 fmol DHA per mg protein with a dissociation constant of 3.9 ± 1.0 nm. However, mean arterial pressure and heart rate determined directly via aortic cannulae, while the rats were conscious and unrestrained, were significantly higher in sp-SHR. Plasma norepinephrine concentration was also significantly higher in sp-SHR. The finding that cardiac beta-adrenergic receptors are unchanged, despite evidence of increased sympathetic nerve activity, suggests that in the sp-SHR there may be a failure of catecholamine-induced “down regulation” of beta-adrenergic receptors. This defect could contribute to the increased cardiac drive in these animals and may thus explain the severity of the hypertension in this strain of spontaneously hypertensive rats.

Original languageEnglish (US)
Pages (from-to)1263-1272
Number of pages10
JournalJournal of Molecular and Cellular Cardiology
Volume12
Issue number11
DOIs
StatePublished - Jan 1 1980

Keywords

  • Beta-receptors
  • Myocardium
  • Spontaneously hypertensive
  • [H]dihydroalprenolol

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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