EFFECT OF LEFT-VENTRICULAR HYPERTROPHY SECONDARY TO CHRONIC PRESSURE-OVERLOAD ON TRANSMURAL MYOCARDIAL 2-DEOXYGLUCOSE UPTAKE - A P-31 NMR SPECTROSCOPIC STUDY

Background This study tested the hypothesis that P-31 nuclear magnetic resonance (NMR)-detectable 2-deoxyglucose (2DG) uptake is increased i n chronically pressure-overloaded hypertrophied left ventricular myoca rdium. Methods and Results P-31 NMR spectroscopy was used to determine the transmural distribution of high-energy phosphate levels and 2-deo xyglucose-6-phosphate (2DGP) accumulation during intracoronary infusio n of 2DG (15 mu mol . kg body wt(-1). min(-1)) in eight normal dogs an d in eight dogs with severe left ventricular hypertrophy (LVH) produce d by ascending aortic banding. The ratio of LV weight to body weight w as 8.25+/-0.65 g/kg in the LVH group compared with 4.35+/-0.11 g/kg in the normal group (P<.01). Myocardial ATP content was decreased by app roximate to 40% and phosphocreatine (PCr) by approximate to 60% in LVH hearts. ATP values were transmurally uniform in LVH and normal hearts , whereas PCr was lower in the subendocardium (Endo) than the subepica rdium (Epi) of both groups. The PCr/ATP ratio was lower in LVH hearts (1.72+/-0.05, 1.64+/-0.07, and 1.53+/-0.10 in Epi, midwall, and Endo, respectively) compared with normal hearts (2.36+/-0.05, 2.09+/-0.06, a nd 1.96+/-0.06; each P<.01 normal versus LVH). Arterial blood levels o f glucose, insulin, and free fatty acids were comparable between group s, whereas arterial lactate and norepinephrine levels were significant ly higher in the LVH group. 2DG infusion did not affect systemic hemod ynamics or myocardial high-energy phosphate or inorganic phosphate lev els in either group. At the end of 60 minutes of 2DG infusion, there w as no detectable accumulation of 2DGP in the normal hearts. However, s even of the eight LVH hearts showed time-depen dent accumulation of 2D GP, which was linearly related to the severity of hypertrophy (r=.90 f or subendocardial 2DGP versus LV weight/body weight). A transmural gra dient of 2DGP was present, with greatest accumulation in the subendoca rdium (3.3+/-1.6, 5.8+/-2.3, and 7.9+/-2.2 mu mol/g in Epi, midwall, a nd Endo of the LVH hearts, respectively; P<.05 Epi versus Endo). Concl usions The pressure-overloaded hypertrophied left ventricle demonstrat ed increased accumulation of 2DGP detected with P-31 NMR spectroscopy. Accumulation of 2DGP was positively correlated with the degree of hyp ertrophy and was most marked in the subendocardium.