RELATIONSHIP BETWEEN ENERGETIC, IONIC, AND FUNCTIONAL STATUS IN THE PERFUSED RAT-HEART FOLLOWING THERMAL-INJURY - A P-31 AND NA-23 NMR-STUDY

To test the hypothesis that energy deficits and intracellular ion dera ngements may be the cellular basis for intrinsic myocardial dysfunctio n in fats after burn trauma, me examined ATP metabolism, intracellular pH, sodium, and mechanical performance simultaneously ill perfused be ating hearts from sham burn or burned rats (43% TBSA, 3 degrees scald burn, resuscitated for 24 hr with lactated Ringer's solution, Parkland formula), Intracellular calcium tvas also measured in my. ocytes harv ested from parallel groups of sham burn and burn resuscitated rats. Bu rn trauma caused a 46% decrease in left ventricular developed pressure , a 69% decrease ill +dP/dt(max), and a 72% decrease in -dP/dt(max). I ntracellular to external standard sodium ratio increased (+58%) from 0 .318 +/- 0.027 to 0.500 +/- 0.048 (P < 0.05), and intracellular calciu m increased (+67%) from 206 +/- 13 to 445 +/- 37 nM (P < 0.01). Burn h eal ts exhibited decreased functional response to isoproterenol challe nge compared to sham burn controls, but energy metabolism was similar in all hearts, regardless of burn injury, Our data suggest that burn t rauma alters intracellular cardiomyocyte calcium and sodium homeostasi s, and ionic derangements are not related to either altered intracellu lar pH or high energy phosphate deficits. (C) 1997 Academic Press.