Prostacyclin Mediation of Vasodilation Following Mesenteric Traction

Abstract

Eight untreated patients (group I) and four patients who received ibuprofen preoperatively (group II) scheduled for elective abdominal aortic aneurysm repair were studied. Heart rate (HR); systolic, diastolic, and mean arterial pressure (MAP); systolic and diastolic pulmonary artery pressure; pulmonary capillary wedge pressure (PCWP); cardiac output (CO); and central venous pressure (CVP) were recorded pre-induction, before mesenteric traction, and 5, 15, and 30 min post-mesenteric traction. Plasma samples were obtained at these times for analysis of six-keto-prostaglandin F1.alpha. (PGF1.alpha.) concentration by radioimmunoassay. Group II patients received ibuprofen 12 mg/kg orally 1 1/2 h before surgery. Plasma samples from six group I patients and all group II patients taken 5 min after mesenteric traction were added to isolated helical strips of cat superior mesenteric arteries precontracted with norepinephrine (200 ng/ml) for analysis of reduction in developed force. In group I, abdominal mesenteric traction resulted in a significant decrease in MAP (P < 0.03) and SVR (P < 0.005) with an increase in CO (P < 0.05) at 5 min post-mesenteric traction, which returned to mean pre-mesenteric traction values by 30 min and a significant increase in PGF1.alpha. concentration. There was a significant positive correlation between PGF1.alpha. and CO (P < 0.001) and a significant negative correlation between PGF1.alpha. and SVR (P < 0.01) at 5 min post-mesenteric traction. Post-mesentric traction plasma samples added to the cat mesenteric artery preparation resulted in vasodilation, as demonstrated by a reduction in developed force of 0.563 .+-. 0.092 grams, as compared to the reduction by pre-mesenteric traction plasma values of 0.12 .+-. 0.11 grams (P < 0.01). Group II patients did not develop significant increases in PGF1.alpha., and 5-min post-mesenteric traction plasma samples did not significantly relax the cat mesenteric artery preparations. There were no changes in MAP, SVR, and CO in group II patients. Flushing of the head and neck in association with mesenteric traction was noted in group I only.