PROSTANOID PRODUCTION IN THE UMBILICOPLACENTAL ARTERIAL TREE RELATIVETO IMPAIRED GLUCOSE-TOLERANCE

The purpose of this study was to investigate prostanoid synthesis in d ifferent segments of the umbilicoplacental vascular tree and its relat ionship to impaired maternal glucose tolerance. Segments from the umbi lical artery and vein, allantochorionic artery branches, and the cotyl edon artery from 21 women with diabetes or impaired glucose tolerance and 10 healthy women were studied. Production of prostacyclin (PGI(2)) and thromboxane (TxA(2)) metabolites was determined. The Mann-Whitney U test, Wilcoxon signed-ranks matched-pairs test, Kruskal-Wallis test , analysis of variance, and simple linear regression analysis were use d. A two-tailed P value of < 0.05 was considered statistically signifi cant. From the umbilical artery distal to the cotyledon artery, the PG I(2) synthesis decreased and the TxA(2) synthesis increased gradually towards the periphery in normal pregnancy. The PGI(2)/TxA(2) ratio was more than 200 times higher in the umbilical artery than in the cotyle don artery. The TxA(2) production tended in general to be higher in th e diabetic group than in the control group, resulting in significantly lower PGI(2)/TxA(2) ratios in some vessels. The prostanoid production was not significantly correlated to maternal HbA(lc) or cord C-peptid e concentrations. The balance between vascular prostacyclin and thromb oxane synthesis in the umbilicoplacental arterial tree changed gradual ly towards the periphery: the more peripheral, the lower the prostacyc lin and the higher the thromboxane production. The physiological role of this phenomenon is unknown, but may be of importance for the equili bration of vascular tone between arteries of different calibers. The a ltered prostanoid balance found in diabetic pregnancy was not directly attributable to the degree of maternal glycemic control, but may refl ect increased free radical activity and peroxide production in diabete s. (C) 1998 Elsevier Science Ireland Ltd.