Inorganic phosphate and coronary perfusion pressure mediate contractile dysfunction during mild ischemia

Masami Miyamae, S. Albert Camacho, William Rooney, Gunner Modin, Hui Zhong Zhou, Michael W. Weiner, Vincent M. Figueredo

Research output: Contribution to journalArticle

Abstract

-During mild graded ischemia in perfused rat hearts, we (V. M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 1794-1802, 1992) previously found a relationship between decreased left ventricular developed pressure (LVDP) and increased Pj, in which intracellular pH, cytosolic Ca2+ concentration ([Ca2+]i), ATP, and free-energy change of ATP hydrolysis were not altered enough to affect contractility. However, the contribution of decreased coronary perfusion pressure (CPP) to decreased LVDP could not be determined. Thus, in the present study, graded hypoxia in perfused rat hearts (95-37.5% 02) was used to increase PI to similar levels produced during mild ischemia without altering CPP and minimizing changes of other potential mediators of contractile dysfunction. 31P-magnetic resonance spectroscopy and indo 1 fluorescence were used to assess energy metabolites and [Ca2+]j, respectively. The relationship between LVDP and PI during graded hypoxia was fit to a monoexponential (LVDP = 105 X e-°-04Pi). These data were compared with the relationship of LVDP and Pj during mild ischemia (LVDP = 106 X e-°-08pO (V. M. Figueredo, R. Brandes, M. W. Weiner, B. M. Massie, and S. A. Camacho. J. Clin. Invest 90: 17941802, 1992). The exponential constant, which describes the effect of Pi on LVDP, was 50% lower during graded hypoxia relative to mild ischemia. This suggests that another mediator, which accounted for -50% of the decrease of LVDP during mild ischemia, was not present during hypoxia. Because CPP decreased during ischemia but not hypoxia, these data suggest that CPP and PI contribute similarly in mediating contractile dysfunction during mild ischemia. hypoxia; calcium; indo 1; Langendorff; magnetic resonance spectroscopy

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume42
Issue number2
StatePublished - 1997
Externally publishedYes

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Ventricular Pressure
Ischemia
Perfusion
Phosphates
Pressure
Magnetic Resonance Spectroscopy
Adenosine Triphosphate
Hypoxia
Hydrolysis
Fluorescence
Calcium

ASJC Scopus subject areas

  • Physiology

Cite this

Inorganic phosphate and coronary perfusion pressure mediate contractile dysfunction during mild ischemia. / Miyamae, Masami; Albert Camacho, S.; Rooney, William; Modin, Gunner; Zhou, Hui Zhong; Weiner, Michael W.; Figueredo, Vincent M.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 42, No. 2, 1997.

Research output: Contribution to journalArticle

Miyamae, Masami ; Albert Camacho, S. ; Rooney, William ; Modin, Gunner ; Zhou, Hui Zhong ; Weiner, Michael W. ; Figueredo, Vincent M. / Inorganic phosphate and coronary perfusion pressure mediate contractile dysfunction during mild ischemia. In: American Journal of Physiology - Heart and Circulatory Physiology. 1997 ; Vol. 42, No. 2.
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AU - Albert Camacho, S.

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AU - Weiner, Michael W.

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