Nitric oxide mediates fluid accumulation during cardiopulmonary bypass

Byline: Kurt E. Wehberg, Andrew H. Foster, Robert M. Wise, Joseph S. McLaughlin, Martha J. Brunner Abstract: Fluid accumulation during cardiopulmonary bypass may be related to the production of endogenous vasoactive substances. We investigated the role of nitric oxide in mediating fluid accumulation during cardiopulmonary bypass. Normothermic cardiopulmonary bypass was carried out for 3 hours in male Sprague-Dawley rats with constant, nonpulsatile flow and hemodilution. Fluid accumulation (rate of change of external reservoir volume) was measured under three experimental conditions: saline solution control (n = 8), l-arginine infusion (n = 6), and N -nitro-l-arginine methyl ester infusion (n = 6). At the end of the experiments, body weight and organ wet/dry ratios were examined. Percentage weight gain was 77% greater in the N -nitro-l-arginine methyl ester group and 23% less in the l-arginine group compared with control values. Fluid accumulation was increased with N -nitro-l-arginine methyl ester after 30 minutes (p < 0.01) and reduced with l-arginine after 120 minutes (p < 0.01) compared with control animals. Water content was significantly decreased in the heart, lung, skin, muscle and peritoneum in rats receiving l-arginine. These data suggest that endogenous nitric oxide plays an important role in minimizing fluid accumulation during cardiopulmonary bypass. (J Thorac Cardiovasc Surg 1996;112:168-74) Article History: Received 26 April 1995; Accepted 7 August 1995 Article Note: (footnote) [star] From the Departments of Surgery and Physiologya and the Division of Thoracic and Cardiovascular Surgery,b University of Maryland Medical System, Baltimore, Md., [star][star] Address for reprints: Andrew H. Foster, MD, University of Maryland School of Medicine, Division of Cardiothoracic Surgery, Room N4W93, 22 S. Green St., Baltimore, MD 21201., a 0022-5223/96 $5.00 + 0, aa 12/1/69253