Effects of meconium and amniotic fluid on contractility of mesenteric artery

Introduction and Aim: Clinical and experimental studies on gastroschisis showed that fetus releases meconium into amniotic fluid and that meconium causes intestinal injury in the fetuses with gastroschisis. The mechanism of injury is not clear. In-vivo and in-vitro studies showed that meconium has an vasoconstrictor effect on umblical vessels and Doppler flow studies of fetuses with gastroschisis showed the differences in superior mesenteric arteries supplying the intestines. Meconium has the potential of ischemia on mesenteric artery with vasoconstriction. This study aimed to determine the effects of the meconium and amniotic fluid on contractility of superior artery that supplying the intestines.Materials and Methods: Fourty-three chicken embryos aged 18 days were used in the study. Only one mesenteric arterial preparate from each embryo prepared and suspended in the organ bath. Mesenteric arterial preparates were divided into three groups. Group 1 (Norepinephrine group, n=6) received cumulative dose of norepinephrine (10-9-10-4 M) and Emax value was determined by dose-response curve. Group 2 (Meconium group, n=30) received meconium suspension at 1/1600, 1/800, 1/400, 1/200 and 1/100 concentrations. Group 3 (Amniotic fluid group, n=8) received clear amniotic fluid. Isometric contractions of mesenteric artery were evaluated.Results: Emax value for norepinephrine on dose-response curve was 10-4 M concentration and maximum isometric contractility response was 298,52±59,27 mg. Maximum mean isometric contraction response in the meconium group was 159,1±41,35 mg) with 1/100 meconium concentration ,and the minimum mean isometric contraction response (98,75±49,03 mg) was found with 1/1600 meconium concentration. In the amniotic fluid group mean isometric contractility response of the mesenteric artery was found 42,1±6,6 mg .Conclusion: Meconium causes vasoconstriction on mesenteric artery although not as much as norepinephrine. It is suggested that direct contact of the amniotic fluid with SMA in gastroschisis can cause ischemic injury in intestines by reducing the blood supply due to vasoconstriction that can be caused by meconium.