Abstract
Changes in ATP and creatine phosphate levels during early (up to 150 s) global ischaemia were determined in isolated rat hearts by two chemical extraction methods (a conventional direct perchloric acid extraction and a stepwise extraction using alcohol and perchloric acid solutions) and by qualitative 31P-NMR. No difference in the ATP content of normally perfused tissue was found using the two chemical extraction methods. The ATP level hardly changed up to 40 s of ischaemia when measured by the three methods, and slightly decreased at 150 s of ischaemia. In the contrast to ATP, creatine phosphate content in the normally perfused tissue was observed to be higher by the stepwise extraction (68-73 nmol/mg protein) than by direct perchloric acid extraction (55 nmol/mg protein). The creatine phosphate rapidly decreased to about 50% of normal value at 40 s of ischaemia, and the difference in the normal creatine phosphate content using the two chemical methods disappeared with the progression of ischaemia. Thus, the creatine phosphate more rapidly decreased when observed by the stepwise method than by the other two methods in this ischaemic condition. These results suggest that (1) creatine phosphate exists in an undetermined state (perhaps neither in simple soluble form nor in so-called "bound" form) in rat cardiac myocytes, and (2) the stepwise extraction method is useful to measure the content of energy metabolites and to examine the intracellular chemical state in cardiac tissues.
Published Version
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