Beta-adrenergic receptor regulation during hypoxia in intact cultured heart cells

Am J Physiol. 1989 Jan;256(1 Pt 2):H275-81. doi: 10.1152/ajpheart.1989.256.1.H275.

Abstract

Regulation of cardiac beta-adrenergic receptors during hypoxia and ischemia is an area of active investigation, with some investigators reporting an increase in sarcolemmal beta-receptor number after ischemia. Previous studies have been limited by the necessity of examining beta-adrenergic receptor properties in membrane preparations from hypoxic or ischemic cardiac tissue and drawing conclusions about receptor localization in intact tissue from the behavior of a fraction of total receptors in membrane populations. As an approach to examining beta-receptor properties under well-defined pathophysiological conditions in intact heart cells, we studied cell-surface beta-receptors and adenylate cyclase activity in intact cultured chick embryo ventricular cells under conditions of controlled hypoxia and reoxygenation. During 2 h of hypoxia (PO2 less than 1.5 Torr) there was a progressive decline in cell surface beta-receptors from 26 +/- 2 to 10 +/- 6 fmol/mg (P less than 0.003) with no change in antagonist or agonist affinity. Receptor number recovered fully during 2 h of reoxygenation. Basal adenosine 3',5'-cyclic monophosphate (cAMP) production was unchanged, but response to isoproterenol in the absence or presence of a phosphodiesterase inhibitor decreased to about half of the response for normoxic cells but fully recovered during reoxygenation in a pattern similar to that for receptor number. Although [ATP] declined significantly during hypoxia (from 35 to 25 nmol/mg), the decline in [GTP] was marginal (4.3 to 3.9 nmol/mg), making it unlikely that substrate for guanine nucleotide regulatory protein was limiting for beta-adrenergic signal transduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / biosynthesis
  • Adenylyl Cyclases / metabolism
  • Animals
  • Carbonyl Cyanide m-Chlorophenyl Hydrazone / pharmacology
  • Cells, Cultured
  • Chick Embryo
  • Cyclic AMP / biosynthesis
  • Heart / drug effects
  • Hypoxia / metabolism*
  • Myocardium / metabolism*
  • Propanolamines / metabolism
  • Propranolol / metabolism
  • Receptors, Adrenergic, beta / metabolism*

Substances

  • Propanolamines
  • Receptors, Adrenergic, beta
  • Carbonyl Cyanide m-Chlorophenyl Hydrazone
  • Adenosine Triphosphate
  • Propranolol
  • Cyclic AMP
  • Adenylyl Cyclases
  • CGP 12177