In vitro renal eicosanoid production during pregnancy in rabbits

The low renal resistance to blood flow in the presence of an activated endogenous renin-angiotensin system in gravid animals may in part be mediated by the action of eicosanoids produced in situ. To evaluate intrarenal eicosanoid production during gestation in rabbits, we quantitated immunoreactive PGE2, 6-keto-PGF1 alpha (a stable metabolite of PGI2) and thromboxane B2 (a stable metabolite of thromboxane A2) in unextracted media after incubation of renal slices and isolated glomeruli. In cortical slices from nonpregnant and pregnant rabbits, PGE2 production (micrograms.g-1.30 min-1) was 0.04 +/- 0.005 and 0.08 +/- 0.01 (P less than 0.01) and 6 keto-PGF1 alpha was 0.03 +/- 0.01 and 0.06 +/- 0.01 (P less than 0.05), respectively. In papillary slices, PGE2 production was 14 +/- 2 and 21 +/- 2 (P less than 0.05) and 6 keto-PGF1 alpha was 4 +/- 1 and 5 +/- 1 (P greater than 0.05) for nonpregnant and pregnant rabbits, respectively. Thromboxane B2 production was unchanged during pregnancy in both cortex and papilla. Acute captopril administration to nonpregnant and to pregnant rabbits in vivo failed to alter in vitro renal slice eicosanoid production. Isolated glomeruli from nonpregnant and pregnant rabbits synthesized PGE2 at similar rates. Exogenous arachidonic acid increased PGE2 production (P less than 0.05), but angiotensin II had no effect on eicosanoid production in vitro. These data suggest that the net synthesis of vasodilator eicosanoids is enhanced during gestation in rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)