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CONTRIBUTION OF SYMPATHETIC ACTIVITY TO LYPOLISIS DURING EXPOSURE TO INCREASING HYPERGRAVITY LOADS.   ^1,2M.M. Moran, ³T.P. Stein and ¹C.E. Wade. ¹NASA Ames Research Center, Moffett Field, CA 94035, ²San Jose State University, San Jose, CA 95192, and ³University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084. 

An increase in catecholamine release from the sympathetic nerves results in lypolysis. The focus of this study was to determine the role of sympathetic catecholamines in the fat loss that occurs during exposure to hypergravity. The study was conducted using 150 g male Sprague-Dawley derived albino rats. Rats were centrifuged at either 1.25 G (n=8), 1.5 G (n=16), 2 G (n=8), or remained at 1 G (n=16). Epididymal fat pads were weighed on day 14 on the study, and urinary epinephrine (E) and norepinephrine (NE) were collected daily and individual samples were pooled. Mean urinary E (picoMoles/day) on days 11-14 in the 2.0 G group (3807 ±322) was significantly (p Ј 0.05) higher than the 1.5 (2179 ±243), 1.25 (1676 ±86), and 1.0 (1749 ±77) G groups. There were no differences in urinary E between the 1.5, 1.25, and 1.0 G groups. Mean urinary NE (picoMoles/day) on days 11-14, was significantly higher in the 2.0 G group (12888 ±774) than the 1.5 (8149 ±604), 1.25 (5743 ±301), and 1.0 (6258 ±426) G groups. NE from the 1.5 G group was higher than the 1.25 and 1.0 G groups and no differences were found in NE between the 1.25 and 1.0 G groups. Mean epididymal fat mass (g/100 g body mass) in the 2.0 (0.694 ±.05), 1.5 (0.780 ±0.2 ), and 1.25 (0.802 ±.04) G groups were significantly less than the 1.0 G (0.905 ±.02) group. The inverse relationship between fat mass and catecholamines suggest that an increase in sympathetic activity contributes to the loss of fat mass that occurs during exposure to hypergravity.