NATRIURESIS AFTER CARDIOPULMONARY BYPASS - RELATIONSHIP TO URODILATIN, ATRIAL-NATRIURETIC-FACTOR, ANTIDIURETIC-HORMONE, AND ALDOSTERONE

Objective: Recent studies suggest that urodilatin from the kidneys rat her than atrial natriuretic factor from the heart is the more importan t member of the family of natriuretic peptides involved in the normal regulation of renal sodium and water excretion, We thus examined the r elationship between natriuresis, urodilatin, and atrial natriuretic fa ctor in patients after cardiopulmonary bypass, a procedure known to in crease levels of atrial natriuretic factor significantly, Methods: Exc retion rates of sodium and water were correlated with the excretion of urodilatin and with circulating levels of atrial natriuretic factor, antidiuretic hormone, aldosterone, and plasma renin activity during a period of 16 hours in 12 patients having had coronary artery bypass op erations and with approximately a 400% elevation in levels of atrial n atriuretic factor, Results: Natriuresis did not correlate with atrial natriuretic factor, antidiuretic hormone, aldosterone, or plasma renin activity. Excretion rates of urodilatin, however, correlated signific antly with excretion rates of sodium (r = 0.74, p = 0.03), urine flow (r = 0.83, p = 0.01), and with levels of serum sodium (r = 0.82, p = 0 .01), Conclusion: These results suggest an important role for urodilat in, greater than that of atrial natriuretic factor, in the regulation of renal excretion of sodium and vater after cardiopulmonary bypass su rgery.