[Prostaglandin E2 receptor and GTP binding protein in the normal and nephrotic rat kidney]

The relationship between prostaglandin E2 (PGE2) receptor and GTP binding protein was studied in the normal and aminonucleoside-induced nephrotic rats. Affinities and maximal binding sites of PGE2 receptors in renal medulla of the male Wistar rats were examined by Scatchard analysis. Cyclic AMP and inositol phosphates were measured in the medulla tissues to examine the intracellular mediators of PGE2 receptor activation. The following results were obtained: 1) GTP gamma S, a nonhydrolyzable guanine nucleotide, increased the 3H-PGE2 binding in a concentration-dependent manner, and pertussis toxin partially attenuated the GTP gamma S effect, 2) PGE2 stimulated the accumulation of inositol phosphates in the medullary tissues with a similar dissociation constant (Kd) value of binding analysis, and high concentrations of PGE2 stimulated the accumulation of cyclic AMP, 3) the affinity of PGE2 receptors in the renal cellular membranes taken from nephrotic rats were significantly lower than that in normal rats, and the effects of GTP gamma S on the affinity was greater in nephrotic rat kidney than normal one. These results suggest that PGE2 receptor of the rat kidney links to a GTP binding protein. In nephrotic rat kidney, damages occur not only in PGE2 receptor but also in the GTP binding protein.