The protective effect of human atrial natriuretic peptide on renal damage during cardiac surgery

Purpose: Acute kidney injury (AKI) is one of the critical complications after cardiac surgery. In the kidney, angiotensin II (Ang II) is formed by independent mechanisms, and activity of the intrarenal renin–angiotensin–aldosterone (RAAS) system contributes to the progression of kidney damage. Although atrial natriuretic peptide (ANP) exerts protective effects against renal injury by inhibiting the RAAS, the mechanisms of this effect have not been completely clarified. We investigated how human ANP (hANP) could prevent renal damage induced by cardiopulmonary bypass. Methods: Forty-eight patients undergoing cardiac surgery were divided into two groups, with and without hANP infusion. Urinary angiotensinogen, neutrophil gelatinase-associated lipocalin (NGAL) and L-type fatty acid-binding protein (L-FABP) were measured during and after surgery in both groups. Plasma renin activity, Ang II, aldosterone and serum creatinine were also measured. Results: Urinary angiotensinogen levels in the hANP group were significantly lower than in the non-hANP group after cardiopulmonary bypass surgery, at the end of surgery and 3 h after surgery. At 3 h after surgery, urinary NGAL levels in the hANP and non-hANP groups were 371.1 ± 413.6 and 761.4 ± 437.8 μg/gCr, respectively (p < 0.01). Urinary L-FABP levels at the end of surgery in the hANP and non-hANP groups were 238.8 ± 107.4 and 573.9 ± 370.1 μg/gCr, respectively (p < 0.01). Moreover, hANP seemed to significantly reduce the incidence of postoperative AKI. Conclusions: hANP demonstrated renal protective effects during cardiac surgery, and could possibly reduce the incidence of AKI after ischemia–reperfusion surgery. Moreover, this protective effect of hANP is likely induced by inhibition of the intrarenal RAAS.