"Calcium paradox" and the effect of varied temperature on its development: a phosphorus nuclear magnetic resonance and morphologic study
Bulkley, B.H.; Nunnally, R.L.; Hollis, D.P.
Laboratory Investigation; a Journal of Technical Methods and Pathology 39(2): 133-140
1978
ISSN/ISBN: 0023-6837 PMID: 682598 Document Number: 128836
Structural injury occurs when myocardium is exposed to Ca2+ after a brief period of Ca2+-free perfusion, but the pathophysiology of Ca paradox and the nature of the cell damage that may occur is a subject of controversy. To study this phenomenon and determine whether or not low temperature which alters Ca2+ flux across cell membranes would inhibit Ca paradox, morphologic methods were combined with the relatively new techniques of P NMR spectroscopy. 31P NMR allowed the myocardial levels of ATP, phosphocreatine and Pi of perfused rat hearts to be studied sequentially and noninvasively during the intervals of normal perfusion, perfusion with Ca2+-free medium and reflow with normal perfusate. The biochemical findings were correlated with morphologic studies on biopsies taken during these intervals. The NMR results at normothermia showed preservation of ATP and phosphocreatine during Ca2+-free perfusion with structural abnormalities limited to cell junctions. With reexposure to Ca2+ there was complete and rapid disappearance of all P resonances and corresponding severe morphologic cell injury virtually identical with ischemia-induced contraction band necrosis. The effect of temperature, determined by performing these studies at 5.degree. intervals from 10-35.degree. C was a progressive inhibition of Ca paradox as the temperature was lowered below 37.degree. C. Inhibition was almost complete at 30.degree. C. Cell death may occur on Ca2+-reexposure and the marked inhibition of this injury by even slight temperature lowering may account for the controversy as to whether Ca paradox is a reversible phenomenon. The value of 31P NMR as a noninvasive method for monitoring phosphate metabolites of myocardium under altered physical and chemical conditions and for obtaining biochemical information that can be directly correlated with morphology is shown.