ATRIAL-NATRIURETIC-PEPTIDE REPLACEMENT THERAPY IN RATS SUBJECTED TO BIATRIAL APPENDECTOMY

The postoperative fluid retention found in some patients after the Cox maze procedure has been attributed to surgically induced loss of atri al natriuretic peptide. We postulated that exogenous atrial natriureti c peptide could reverse this antidiuresis. A rat model was used to inv estigate this hypothesis, In group I, the sham group, the atrial appen dages were left intact and the animals were then subjected to a fluid challenge equivalent to 1% of the animal's body weight. In group II, a fter biatrial appendectomy, the animals were subjected to a fluid chal lenge similar to that in group I. Animals in group III underwent the s ame protocol as that for group II plus intravenous administration of a triopeptin III at varying concentrations, Urine output and plasma atri al natriuretic peptide levels were significantly decreased after biatr ial appendectomies (p less than or equal to 0.01). Urine output return ed to control levels after biatrial appendectomies with low-dose atria l natriuretic peptide infusion (0.5 pmol/min = 25.5 pg/min), although circulating atrial natriuretic peptide levels were lower, Urine output and plasma atrial natriuretic peptide levels increased with atrial na triuretic peptide infusions between 0.5 and 50 pmol/min. Heart rate an d mean blood pressure did not vary significantly with atrial natriuret ic peptide infusions. Thus atrial natriuretic peptide can be used effe ctively in low doses to induce a diuresis after biatrial appendectomie s, Atrial natriuretic peptide may have clinical application after the Cox maze procedure.