PGE2 Synthesis in Cultured Renal Papillary Collecting Tubule Cells from Young and Aged Spontaneously Hypertensive Rats

Abstract

To investigate whether altered renal medullary prostaglandin (PG) synthesis is involved in the development of hypertension in spontaneously hypertensive rats (SHR), we compared the capacity of PGE2 synthesis in cultured renal papillary collecting tubule cells from young (4-week-old) and aged (16-week-old) SHR and control Wistar-Kyoto rats (WKY). Basal levels of PGE2 synthesis were lower in young SHR cells than in WKY cells (p less than 0.001). Arachidonic acid-stimulated PGE2 synthesis, however, had a slight tendency to be higher in SHR cells than in WKY cells. Bradykinin- and A23187-stimulated PGE2 synthesis were similar in both strains. Basal levels of cyclic AMP were also lower in young SHR cells than in WKY cells (p less than 0.001), but the cAMP response to exogenous PGE2 was equal between the strains. In papillary collecting tubule cells from aged rats, basal levels of PGE2 and cyclic AMP as corrected for cellular protein were significantly lower than those in young rats, but there was no difference between the strains. Urinary excretion of PGE2 and thromboxane B2 was equal in aged SHR and WKY. These results suggest that papillary collecting tubule of young SHR and WKY may differ in the metabolism of PGE2 and cyclic AMP. This difference may be attributed to the possible defect in arachidonate availability in SHR.