Beta-adrenergic receptor characteristics of postnatal rat myocardial cell preparations

Allison A. Welder, Tina K. Machu, Steven W. Leslie, Richard E. Wilcox, June Bradlaw, Daniel Acosta

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Primary mycolardial cell cultures and freshly isolated cardiac cells in suspension resprensent two isolated, whole cell models for investigating cellular transsarcolemmal45Ca++ exchange in response to a receptor-coupled stimulus. Studies were performed to characterize beta-adrenergic receptor binding, beta-adrenergic receptor mediated cellular calcium (45Ca++) exchange, and viability in purified primary myocardial cell cultures and freshly isolated cardiac cells in suspension obtained from 3-to 3-d-old Sprague-Dawley rats. In addition, beta-adrenergic receptor binding was characterized in whole-heart crude membrane preparations. All three preparations had saturable beta-adrenergic binding sites with the antagonist [125I]iodopindolol ([125I]IPIN). The suspensions had a significantly lower B max (42±6 fmol/mg protein) than the membranes and cultures (77±8 and 95±10 fmol/mg protein, respectively). The K D of the cultures (218±2.0 p M) was significantly higher than that for the suspensions (107 ±1.3 p M) and membranes (93±1.3 p M). Viability was significantly lower in the suspensions (57%) when compared to 94% viability in myocardial cell cultures after 3 h of incubation in Kreb's Henseleit buffer. Incubation of the cultures with 5.0×10-7 M isoproterenol resulted in a significant increase in45Ca++ exchange as early as 15 s. In contrast,45Ca++ exchange into the suspensions was not increased. Although both primary cell cultures and cardiac cells in suspension possess saturable beta-adrenergic receptors, only the monolayer cultures exhibited functional beta-adrenergic receptor-mediated45Ca++ exchange. Of the two intact cell models investigated, these data suggest that primary myocardial cell cultures are more suitable than cell suspensions for investigating beta-adrenergic receptor binding and functions in the postnatal rat heart.

Original languageEnglish
Pages (from-to)771-777
Number of pages7
JournalIn Vitro Cellular & Developmental Biology
Volume24
Issue number8
DOIs
StatePublished - 1 Aug 1988

Keywords

  • [I]iodopindolol
  • beta-adrenergic receptor
  • calcium (Ca) exchange
  • cardiac cell suspensions
  • ioproterenol
  • myocardial cell cultures
  • postnatal
  • viability

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