Impaired Ca2+ handling is an early manifestation of pressure-overload hypertrophy in rat hearts

Kevin C. Chang, Joop H.M. Schreur, Michael W. Weiner, S. Albert Camacho

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Both cytosolic free Ca2+ ([Ca2+](i)) decline and myocardial relaxation are slowed in severe hypertrophy and heart failure. However, it is not certain whether this occurs in mild to moderate hypertrophy. Therefore, we tested the hypotheses that slowing of [Ca2+](i) decline 1) occurs in mild to moderate hypertrophy, 2) occurs in the absence of slowed relaxation, and 3) is related to the degree of hypertrophy. Experiments were performed on isolated rat hearts subjected to pressure overload. Indo 1 fluorescence was used as an index of [Ca2+](i). [Ca2+](i) decline and myocardial relaxation were assessed by the time constant of expoential [Ca2+](i) decline (τ(Ca)) and left ventricular (LV) pressure decline (τ(P)), respectively. Mean τ(Ca) was significantly increased in hearts from banded rats compared with sham-operated rats (59 ± 13 vs. 45 ± 5 ms, P = 0.03). In contrast, there was no difference in mean τ(P) (28 ± 3 vs. 29 ± 5 ms, P = not significant). There was a linear relationship between τ(Ca) and LV dry weight (r = 0.79). In summary, slowing of the [Ca2+](i) transient decline occurred in mild to moderate hypertrophy. However, LV relaxation was unaffected. Furthermore, slowing of the [Ca2+](i) transient decline was closely related to the degree of LV hypertrophy. These data suggest that slowing of [Ca2+](i) decline is an early manifestation of pressure-overload hypertrophy that precedes slowing of relaxation.

Original languageEnglish (US)
Pages (from-to)H228-H234
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume271
Issue number1 40-1
DOIs
StatePublished - Jul 1996
Externally publishedYes

Keywords

  • fluorescent dyes
  • indo 1-acetoxy-methyl ester
  • myocardial relaxation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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