Effect of exercise training on intracellular free Ca2+ transients in ventricular myocytes of rats

M. H. Laughlin, M. E. Schaefer, M. Sturek

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

The purpose of this study was to test the hypothesis that exercise training induces enhanced intracellular free Ca2+ (Ca(i)) availability to the contractile elements of cardiac cells. Ca(i) transients were directly measured in single isolated contracting ventricular myocytes from exercise- trained (EX) and sedentary control (SED) rats. Male Sprague-Dawley rats underwent 16 wk of progressive treadmill exercise (32 m/min, 8% grade, 1.5 h/day) (EX) or were cage confined (SED). EX rats had lower resting heart rate and elevated skeletal muscle oxidative capacity. Ca(i) was measured with the fluorescent Ca(i) indicator fura-2. Simultaneous video monitoring indicated that myocytes suspended in physiological salt solution were quiescent until stimulated electrically at a frequency of 0.2 Hz (12-36 V, 2-ms duration). Stimulated Ca(i) transients, measured from changes in fura-2 fluorescence, were similar in cells from EX and SED groups. Peak shortening, time to peak shortening, velocity of shortening, contraction duration, and time to half- relaxation were also similar in cells from EX and SED rats. Ryanodine (10 μM) was applied to eliminate the contribution of Ca2+ release from sarcoplasmic reticulum to the Ca(i) transient. Verapamil was applied to eliminate the contribution of voltage-gated Ca2+ channels to Ca(i) transients. Ca(i) transients were also similar in cells from EX and SED groups after these pharmacological interventions. These results suggest that treadmill training of rats does not alter Ca(i) availability to the contractile elements in isolated ventricular myocytes.

Original languageEnglish (US)
Pages (from-to)1441-1448
Number of pages8
JournalJournal of Applied Physiology
Volume73
Issue number4
StatePublished - Jan 1 1992
Externally publishedYes

Keywords

  • calcium influx
  • calcium release channel
  • contractility
  • ryanodine
  • verapamil
  • voltage-gated calcium channel

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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