Dynamic changes in Gα(i-2) levels in rat hearts associated with impaired heart function after myocardial infarction

B. Shi, J. E. Heavner, K. K. McMahon, J. E. Spallholz

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15 Scopus citations

Abstract

The objective of this study was to determine if levels and function of G(s)α and Gα(i-2) in rat hearts change over time following acute myocardial infarction (MI), and if so, whether the changes in G proteins are associated with changes in heart function. As compared with sham-operated controls, the Gα(i-2) level of MI rats did not change at day 1, increased by 64% at day 3 (P < 0.01) and by 55% at day 9 (P < 0.05) accompanied by reduced adenylyl cyclase activity, and returned to control by day 21. By contrast, the G(s)α level did not change at any time. Cardiac function in MI animals was markedly impaired at days 1, 3, and 9 as evidenced by substantial elevation in LVEDP and reduction in maximum rates of pressure development and relaxation, and was partially restored at day 21. Increased Gα(i-2) level in MI rats correlated significantly to severity of impaired cardiac function. The results show a three-phase dynamic pattern in Gα(i-2) level following acute MI: a lag phase, an increased expression phase associated with marked impairment of heart function, and a late phase in which the expression returns to control level accompanied by partially restored cardiac function.

Original languageEnglish
Pages (from-to)H1073-H1079
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume269
Issue number3 38-3
DOIs
StatePublished - 1995

Keywords

  • G proteins
  • adenylyl cyclase
  • coronary artery occlusion
  • heart failure
  • left ventricular function

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