Patterns of sodium excretion during sympathetic nervous system arousal.
The purpose of this study was to examine Na+ handling and regulation during 1 hour of behaviorally induced sympathetic nervous system (SNS) arousal followed by 2 hours of recovery. Two patterns of response were observed among experimental subjects, despite similar changes in blood pressure and heart rate. In one group (n = 19), Na+ excretion increased significantly during SNS arousal, which then decreased significantly during recovery (12.3 versus 16.0 versus 13.1 meq/hr, baseline, SNS arousal, recovery, respectively). Changes in Na+ excretion were correlated with changes in creatinine clearance from baseline to SNS arousal (r = 0.54) and SNS arousal to recovery (r = 0.58), and were accompanied by significant increases in plasma renin activity (1.5 versus 2.0 ng/ml/hr) and aldosterone (8.5 versus 10.3 ng/ml/hr) from baseline to SNS arousal. Na+ excretion decreased during SNS arousal in the other group of subjects (n = 17) and remained below baseline levels during recovery (16.2 versus 12.7 versus 11.9 meq/hr). These changes were associated with significant decreases in creatinine clearance from baseline to recovery (138 versus 121 ml/min/1.73 m2) and significant increases in plasma renin activity from baseline to SNS arousal (1.3 versus 2.2 ng/ml/hr) but not in aldosterone. Control subjects (n = 24) maintained baseline levels of each variable throughout the procedure. These results suggest that individuals differ in Na+ handling and regulation during behavioral arousal. Decreases in Na+ have been reported previously in humans and animals at risk for the development of hypertension.
Harshfield
G A
GA
Department of Pediatrics, University of Tennessee, Memphis 38103.
Pulliam
D A
DA
Alpert
B S
BS
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000450:Aldosterone / Q000097:blood; D001794:Blood Pressure; D003404:Creatinine / Q000378:metabolism; D006339:Heart Rate; D006801:Humans; D008297:Male; D009318:Natriuresis; D011188:Potassium / Q000652:urine; D012083:Renin / Q000097:blood; D013564:Sympathetic Nervous System / Q000502:physiology*
D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D003404:Creatinine; D012083:Renin; D011188:Potassium