Effect of exogenous phospholipase A2 and triacylglycerol lipase on the synthesis and release of monoenoic and bisenoic prostaglandins from isolated rat uterus.

The possible existence of a selective and independent mechanism subserving the formation of prostaglandin E1 (PGE1) and of prostaglandin E2 (PGE2) has been reported in previous studies from our group. In the present experiments we have demonstrated that neutral lipid lipases play an important role yielding dihomo-gamma-linolenic acid for the formation of PGE1. Indeed, exogenous triglyceride lipase added to the incubation bathing solution at a concentration of 150 U/ml increased several fold the production of PGE1 by isolated uterine strips obtained from spayed rats. Nevertheless the presence of the enzyme did not modify significantly the synthesis and release of bisenoic PGs (PGE2 and PGF2 alpha). When triarachidonin was added, as an artificial substrate into the incubating medium in order to detect the presence of endogenous triacylglycerol lipase, we observed a significant increment in the generation of PGE2 (p less than 0.005) and of PGF2 alpha (p less than 0.001) without evident changes in the basal release of PGE1. On the other hand, the addition of phospholipase A2 (PLA2) at 0.2 U/ml, increased significantly the production of PGE2 (p less than 0.001) but failed to alter the concentration of PGE1 in the incubating solution. Surprisingly, PLA2 did not enhance the synthesis of PGF2 alpha in the present experiments, a situation for which we do not have a clear explanation. Exogenous bradykinin (10(-6) M), a well known stimulant of PLA2 activity in several tissues, also increased significantly (p less than 0.001) the production of PGE2 without altering that of PGE1.(ABSTRACT TRUNCATED AT 250 WORDS)

Defects in the prostaglandin-system--heredity, prevalence and vascular risk analysis.

2180 healthy adults, 620 patients (90% with cardiovascular disease, 10% others), 143 newborns and 351 relatives of persons in whom any abnormality of the prostaglandin (PG)-system had been discovered were involved in the Viennese Initiative for Prostaglandin (VIP)-Screening from 1984 through May 1989. The defects discovered were either inborn or acquired ones and were either familial or non-familial. The highest number of defects (54.8% of the total) identified were associated with PGI2. They indicated a lack of the PGI2-synthesis stimulating plasma factor (PF)-activity (n = 17) and PGI2-stabilizing capacity in plasma (defect 'Vienna-Döbling', n = 4, 12.9% of total), absence of high-affinity PGI2-binding sites on platelet membranes and lack of response of platelets to PGI2 (defect 'Vienna-Hietzing', n = 2, 6.5% of total). Furthermore, a lack of cyclooxygenase (n = 2, 6.5% of total), 12-lipoxygenase (defect 'Vienna-Penzing', n = 3, 9.7% of total) and thromboxane synthetase (n = 3, 9.7% of total) activities were diagnosed. In newborn screening, the PF-absence amounted to 2.8% (4/143), the lack of PGI2-stabilizing capacity to 0.7% (1/143). In adults, the prevalence is difficult to assess. Nevertheless, our findings indicate a frequency of 0.93% (26/2800) of defects in the PG-system among the adult Viennese population. The lack of PF-activity seems to be by far the most frequent one (0.46%, 13/2800). Other defects are much less common. It is not clear whether the incidence in healthy subjects or in patients with cardiovascular disease is different from each other. Further, it remains to be assessed whether there is a causative relation to vascular events or just an association. More intensive screening activities should validate the diagnostic, pathogenetic and therapeutic impact of the various defects in the PG-system.