ENERGY-METABOLISM OF THE HEART AND THE LIVER IN BRAIN-DEAD DOGS AS ASSESSED BY P-31 NMR-SPECTROSCOPY

The energy metabolism of the heart and the liver was assessed in brain- dead dogs by 31P nuclear magnetic resonance spectroscopy. The mean blood pressure and pulse rate changed respectively from 136.1 ± 9.3 mm Hg (mean ± SEM) and 126.7 ± 4.4/min in the control period, to 212.9 ± 15.8 mm Hg and 146.7 ± 13.3/min during Cushing phenomenon (CU period), and to 60.0 ± 6.4 mm Hg and 60.0 ± 2.9/min after completion of brain death (BD period). The ratio of creatine phosphate to inorganic phosphate (PCr/P(i)) of the heart decreased from 5.00 ± 1.08 to 3.24 ± 0.80 in the CU period and increased to the levels of the control values in the early BD period. The intracellular pH of the heart decreased from 7.20 ± 0.07 to 6.91 ± 0.02 in the CU period and increased to 7.12 ± 0.01 in the BD period. The positive relationship between the P(i)/PCr and the rate-pressure product (BP x PR) indicates that the regulation of the oxidative metabolism by free ADP was well maintained except at some points in the CU period (P(i)/PCr = 8.77 x 10-6 BP x PR+0.164, r = 0.704). This suggested that the remarkable hypotension and bradycardia in the BD period is not associated with cardiac energy failure. Although the energy states of both the heart and the liver in brain-dead dogs were adequately maintained in the BD period, the changes were different. While the PCr/P(i) of the heart changed rapidly and significantly in response to the changes in hemodynamics, the β-ATP/P(i) of the liver changed gradually and to a smaller extent. © 1994 Academic Press. All rights reserved. © 1994 Academic Press. All rights reserved.