Background: The relationship between urinary vasoactive factors and sodium excretion has not been adequately addressed in humans. Procedure: Excretion rates of sodium, nitrates/nitrites (NOx), cGMP, and endothelin-1 (ET-1) were measured before and after ingestion of a mixed electrolyte solution (8 oz Gatorade) while undergoing a routine cardiovascular evaluation in a sample of 51 normotensive young adults. Results: Significant correlations were detected for changes in excretion between all four variables, r ranged from 0.50 to 0.86 (P < .001). Correlations were higher in African Americans than white Americans. Conclusions: The association of renal ET-1 and NO activity with sodium excretion supports the hypothesis that these factors play a role in the physiologic response to acute changes in sodium intake, particularly in African Americans. © 2001 American Journal of Hypertension, Ltd.