[Influence of labetalol on the resistance of human fetoplacental vessels in perfusion in vitro].

Objectives: The main unfavourable effects observed in gestosis include: increased vascular peripheral resistance and increased blood pressure with a defective uteroplacental flow. The above mentioned changes may result from disorders in prostacyclin PGI2/thromboxane A2 balance.

Design: The aim of the studies presented was to compare the effects of, labetalol on the fetal vascular resistance induced by U 46,619--stable analogue of thromboxane A2 an experimental bilateral perfusion of the human placental lobule.

Materials And Methods: The researchers used the experimental model described by Schneider. 12 perfusions of the human placental lobules were performed. The control and labetalol groups consisted in 6 placental lobule perfusions lasting 120 min each. Having obtained constant increase in perfusion pressure from the 60th min of the experiment, labetalol was administered along with thromboxane A2 analogue into the fetal circulation. The perfusion pressure was steadily recorded on the kymograph tape.

Results: The stable increase of perfusion pressure was observed from the 60th minute with the average of 185% of the initial pressure. This value represented the reference standard in the second stage of the studies in which the effects of labetalol on the experimentally increased perfusion pressure was evaluated.

Conclusions: Labetalol did not significantly affect the hemodynamics of fetoplacental vessels.