Uptake of P32 by Cardiac Muscle in Vivo

Abstract

The incorporation of P32 into the inorganic and acid-labile phosphate fractions of dog heart muscle was studied, using a technic of needle biopsy of the heart under local anesthesia. The increased cardiac work associated with muscular exercise resulted in an increased rate of P32 uptake and an increase in the rate of attainment of isotope equilibrium between the acid-labile and the inorganic phosphate fractions. No such increases were observed in 6 dogs with an elevated cardiac work load following the production of a large arteriovenous fistula. It was also found that the specific activities of the acid-labile and phosphocreatine phosphate fractions were higher than that of the inorganic phosphate fraction, 5-15 mins. after admn. of P32. The specific activity of the terminal phosphate group of ATP was significantly higher than that of the intermediate phosphate group.