The vasoactive properties of ascitic fluid in acute pancreatitis in a porcine model.

The hemodynamic effect of pancreatic ascitic fluid was studied in a porcine model. Pancreatitis was induced by a low-pressure infusion of trypsin and taurocholate sodium into the pancreatic duct. The ascitic fluid that accumulated was then injected into the inferior vena cava of five pigs, with each pig receiving five infusions at 40-minute intervals. Mean arterial blood pressure and peripheral vascular resistance fell with each infusion, while pulmonary artery pressure increased. The magnitude of the drop in arterial blood pressure decreased with subsequent infusions, suggesting tachyphylaxis. The rise in pulmonary artery pressure increased with successive infusions. Anesthesia artifact and decay of the pancreatic ascitic fluid were ruled out as causes of the tachyphylaxis. Filtration separated the substances producing pulmonary effects and systemic blood pressure effects (0.2 to 11 microns vs 10,000 daltons to 0.2 micron). These data suggest that two mediators may produce the hemodynamic effects of pancreatic ascitic fluid.