The effect of amniotic fluid on the human omental artery in vitro,

Objective: The aim of the study was to determine the effect of amniotic fluid on the in vitro contractility of the human omental artery. Study Design: Amniotic fluid and a segment of omentum were obtained from each of 5 patients at the time of planned cesarean delivery at normal term gestation for the indication of previous cesarean delivery. The omental artery was cleaned and cut into 3-mm rings, which were placed in 10-mL organ chambers for isometric tension recording. The chambers were filled with Krebs-Henseleit solution bubbled with 5% carbon dioxide in air and maintained at 37° C, pH 7.4. The rings were then equilibrated at 1 g passive tension for 90 minutes. The amniotic fluid was centrifuged for 10 minutes at 3000 rpm to remove all debris. Increasing volumes of supernatant (10-2000 μL) were added to the omental artery rings at baseline tone or after contraction with U46619 (10–7 mol/L) or potassium chloride (60 mmol/L) to detect contractile and relaxant effects, respectively. Time-solvent control preparations were also run in parallel. Results: Amniotic fluid had no effect on the basal tone of omental artery rings. Amniotic fluid had no effect on the tension in rings previously contracted with either U46619 or potassium chloride. Conclusions: Amniotic fluid has no direct effect on isolated human omental artery. The catastrophic hemodynamic changes associated with the syndrome of amniotic fluid embolism are not due to a direct effect of circulating amniotic fluid on vascular tone but rather may be due to secondary responses (Am J Obstet Gynecol 1999;180:454-6.)