Prostaglandin e biosynthesis in the dahl rat renal papilla stimulus-dependent response

The prostaglandin system influences renal sodium and water excretion and appears to be more active in the Dahl salt-resistant (DR) than salt-sensitive (DS) rat. During an investigation of renal papillary prostaglandin E (PGE) biosynthesis in DR and DS rats, it was noted that the PGE response to specific stimuli was dependent on the type of stimulus ap­plied. Rats fed either a 0.3% of 4% NaCl diet from 3 weeks of age were killed at 13 to 15 weeks of age. The renal papilla was sectioned and incubated in Krebs-Henseleit buffer. We stimulated PGE biosyn­thesis by incubation of tissues in hyperosmolal buffer (1500 mOsm NaCl) or in the presence of furosemide (3 mmol/L). PGE production was de­termined by radioimmunoassay of the incubation buffer. The PGE biosynthesis in response to hy­perosmolality was significantly greater in the groups fed the 4% NaCl diet, independent of rat strain. The PGE biosynthesis in response to furo­semide was significantly greater in each group of DR rats, independent of dietary NaCl. These resuls suggest that in the renal papilla of the Dahl rat stimulation-secretion coupled PGE biosynthesis is dependent not only on genetic determinants but also on the type of stimulus applied. Am J Hyper- tens 1991;4:76-80.