Short-term effects of human orthotopic heart transplantation on hormones regulating fluid and electrolyte balance.

Hormonal regulation of fluid and electrolyte homeostasis and blood pressure is under the auspices of three organs: the heart, the brain, and the kidneys. Their regulatory roles are fulfilled by the actions of atrial natriuretic peptide (ANP), vasopressin, and the renin-angiotensin-aldosterone system (RAAS), respectively. The aim of this study was to appreciate the short-term effects of orthotopic human heart transplantation on the release of these hormones. Alpha-ANP, renin, aldosterone, and vasopressin serum levels were assessed by radioimmunoassay before and during the 10 days after grafting in a series of 10 patients. On day 1, alpha-ANP levels dropped from 42.4 +/- 6.5 to 25.1 +/- 2.2 fmol/ml before returning to levels comparable with those found before transplantation. This decrease in alpha-ANP levels was associated with a peak in vasopressin and aldosterone levels. With the exception of the peak in vasopressin levels seen on day 1, preoperative and postoperative levels of this hormone were near normal. Increased preoperative renin levels dropped significantly as of day 5 (from 268 +/- 99 to 122 +/- 66 ng/L). This decrease was related to improved patient hemodynamic status. No significant correlation was found between the changes in alpha-ANP levels, RAAS or vasopressin levels, patient hemodynamic status, or administered drugs. In conclusion, grafted heart tissue was capable of high alpha-ANP release early on. The drop in alpha-ANP serum levels, compared with the peaks in vasopressin and aldosterone on day 1, might have been caused by the ability of the graft to play a role in the hormonal regulation of fluid and electrolyte balance.(ABSTRACT TRUNCATED AT 250 WORDS)