PGE2, PGF2 alpha, 6-keto-PGF1 alpha, and TxB2 synthesis along the rabbit nephron

The capacity of synthesis of prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), 6-keto-PGF1 alpha, and thromboxane (TxB2) along the rabbit nephron was determined. A sensitive enzyme immunoassay was applied to isolated nephron segments, from the glomerulus to the terminal collecting tubule. The three prostaglandins and thromboxane (PG) were measured on the same samples after incubation in the presence of arachidonic acid. In the glomerulus, PGE2 synthesis (29.4 +/- 3.3 pg X glomerulus-1 X 30 min-1) represented 60% of the sum of the four PGs. PGF2 alpha and 6-keto-PGF1 alpha represented 22 and 17%, respectively, and TxB2 1.4%. The contribution of each PG to tubular synthesis was different, since at least 90% of PG synthesis consisted of PGE2. In the medullary collecting tubule (MCT), by far the major tubular site of PG synthesis, it was 809.6 +/- 140.8 pg X mm-1 X 30 min-1 for PGE2, 17.7 +/- 7.2 for PGF2 alpha, 8.3 +/- 1.9 for 6-keto-PGF1 alpha and 0.24 +/- 0.08 for TxB2. These relative proportions were roughly respected all along the tubule. Values were much lower in the convoluted and straight portions of the proximal tubule (proximal convoluted tubule: PGE2 8.2 +/- 2.0, PGF2 alpha 0.4 +/- 0.06, 6-keto-PGF1 alpha 0.26 +/- 0.04, TxB2 0.017) and the medullary and cortical thick ascending limb of the loop. They increased regularly along the distal structures of the tubule (light portion of the cortical collecting tubule (CCT1): PGE2 228.3 +/- 20.4, PGF2 alpha 4.34 +/- 0.6, 6-keto-PGF1 alpha 1.8 +/- 0.3, TxB2 0.22 +/- 0.07).(ABSTRACT TRUNCATED AT 250 WORDS)