Meeting Abstract

P1.69  Jan. 4  Role of Prostaglandins in the Patency of the Ductus Arteriosi of the Chicken Embryo (Gallus domestics) GREYNER, HJ*; DZIALOWSKI, EM; Univ. of North Texas, Denton; Univ. of North Texas, Denton hjg0008@unt.edu

The ductus arteriosi (DA) in the chicken embryo (Gallus domestics) are two vessels that originate at the pulmonary arches and connect with the descending aorta. Their function is to shunt blood away from the nonventilated lungs and towards the body and the choriallantoic membrane. During hatching they close so that the embryo�s circulation resembles that of the adult. In mammals, there is strong evidence that points at prostaglandins having a role in maintainin ductal patency prior to birth. Here we examined the role of prostaglandins in the chicken DA patency. Prostaglandins are made in the cyclooxygenase pathway with the help of cyclooxygenase (COX) enzymes present in two isoforms, COX1 and COX2. Therefore, if prostaglandins have a role in keeping the avian DA patent then blocking the cyclooxygenase pathway should cause contraction of the DA. To examine this we exposed isolated DA rings to indomethacin, a non-selective inhibitor of COX. The chicken ductus was insensitive to indomethacin, even during long exposures of up to 3 hours. However, we found that during these long-term exposures to a gas mixture containing 30% O₂ the vessel contracted. To test the response of the DA to specific prostaglandins, we exposed in vitro pre-contracted DA rings to prostaglandin E₂, I₂, F_2α and D₂ and recorded the subsequent changes in tension. Prostaglandin E₂ produced a contractile response of the DA at a concentration of 10^-6 M. Prostaglandin F_2α also caused contraction of the DA at high concentrations (10^-5 M). It appears that prostaglandins have a reduced role in maintaining DA patency in the avian system compared with the mammalian DA. This research was supported by an NSF grant (IOB0417205) awarded to EMD.