Abstract
Hypertrophied hearts have enhanced susceptibility to ischemia-induced contractile dysfunction. To explore the mechanisms of this phenomenon, we studied the effect of acidosis on the Ca2+ sensitivity of the contractile proteins and on Ca2+ accumulation by the sarcoplasmic reticulum (SR) in chemically (saponin) skinned cardiac fibers obtained from normal and pressure-overload hypertrophied rat left ventricles. Left ventricular pressure overload was induced by partial ligation of the abdominal aorta 6-8 wk before study. Age- and weight-matched normal rats served as controls. Pressure overload increased the left ventricular weight-to-body weight ratio by 48%. Reduction in pH shifted the pCa-tension curve to the right similarly in normal and hypertrophied preparations, and there was no difference in pCa-tension relationship at pH 7.0 or 6.5 between the two groups. However, reducing the pH of 1 μM Ca2+-loading solution from 7.0 to 6.5 decreased the amount of Ca2+ accumulated in the SR to 66.2 ± 3.0% in normal fibers and 43.2 ± 4.0% in hypertrophied fibers (P < 0.01). We conclude that the enhanced susceptibility of hypertrophied hearts to ischemia-induced diastolic dysfunction may be partly explained by the greater depressing effect of acidosis on Ca2+ accumulation by the SR.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Heart and Circulatory Physiology |
| Volume | 259 |
| Issue number | 4 28-4 |
| State | Published - Jan 1 1990 |
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Keywords
- aortic constriction
- calcium sensitivity
- chronic pressure overload
- sarcoplasmic reticulum
ASJC Scopus subject areas
- Physiology
Cite this
Effect of acidosis on contractile system in skinned fibers of hypertrophied rat heart. / Kimura, S.; Bassett, A. L.; Furukawa, T.; Furukawa, N.; Myerburg, Robert J.
In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 259, No. 4 28-4, 01.01.1990.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effect of acidosis on contractile system in skinned fibers of hypertrophied rat heart
AU - Kimura, S.
AU - Bassett, A. L.
AU - Furukawa, T.
AU - Furukawa, N.
AU - Myerburg, Robert J
PY - 1990/1/1
Y1 - 1990/1/1
N2 - Hypertrophied hearts have enhanced susceptibility to ischemia-induced contractile dysfunction. To explore the mechanisms of this phenomenon, we studied the effect of acidosis on the Ca2+ sensitivity of the contractile proteins and on Ca2+ accumulation by the sarcoplasmic reticulum (SR) in chemically (saponin) skinned cardiac fibers obtained from normal and pressure-overload hypertrophied rat left ventricles. Left ventricular pressure overload was induced by partial ligation of the abdominal aorta 6-8 wk before study. Age- and weight-matched normal rats served as controls. Pressure overload increased the left ventricular weight-to-body weight ratio by 48%. Reduction in pH shifted the pCa-tension curve to the right similarly in normal and hypertrophied preparations, and there was no difference in pCa-tension relationship at pH 7.0 or 6.5 between the two groups. However, reducing the pH of 1 μM Ca2+-loading solution from 7.0 to 6.5 decreased the amount of Ca2+ accumulated in the SR to 66.2 ± 3.0% in normal fibers and 43.2 ± 4.0% in hypertrophied fibers (P < 0.01). We conclude that the enhanced susceptibility of hypertrophied hearts to ischemia-induced diastolic dysfunction may be partly explained by the greater depressing effect of acidosis on Ca2+ accumulation by the SR.
AB - Hypertrophied hearts have enhanced susceptibility to ischemia-induced contractile dysfunction. To explore the mechanisms of this phenomenon, we studied the effect of acidosis on the Ca2+ sensitivity of the contractile proteins and on Ca2+ accumulation by the sarcoplasmic reticulum (SR) in chemically (saponin) skinned cardiac fibers obtained from normal and pressure-overload hypertrophied rat left ventricles. Left ventricular pressure overload was induced by partial ligation of the abdominal aorta 6-8 wk before study. Age- and weight-matched normal rats served as controls. Pressure overload increased the left ventricular weight-to-body weight ratio by 48%. Reduction in pH shifted the pCa-tension curve to the right similarly in normal and hypertrophied preparations, and there was no difference in pCa-tension relationship at pH 7.0 or 6.5 between the two groups. However, reducing the pH of 1 μM Ca2+-loading solution from 7.0 to 6.5 decreased the amount of Ca2+ accumulated in the SR to 66.2 ± 3.0% in normal fibers and 43.2 ± 4.0% in hypertrophied fibers (P < 0.01). We conclude that the enhanced susceptibility of hypertrophied hearts to ischemia-induced diastolic dysfunction may be partly explained by the greater depressing effect of acidosis on Ca2+ accumulation by the SR.
KW - aortic constriction
KW - calcium sensitivity
KW - chronic pressure overload
KW - sarcoplasmic reticulum
UR - http://www.scopus.com/inward/record.url?scp=0025089505&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0025089505&partnerID=8YFLogxK
M3 - Article
VL - 259
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
SN - 0363-6143
IS - 4 28-4
ER -