In vivo flux between phosphocreatine and adenosine triphosphate determined by two-dimensional phosphorous NMR.

The in vivo unidirectional flux between creatine phosphate and ATP was determined in the leg and head of the anesthetized rat using a two-dimensional NMR technique. The unidirectional flux of creatine phosphate to ATP was 13 mumol/s/g-weight in the leg and 2 mumol/s/g-weight in the head. The unidirectional flux between ATP and inorganic phosphate was too slow to be detected and was estimated to be less than 0.1 mumol/s/g-weight.