IMCD CELLS CULTURED FROM DAHL-S RATS ABSORB MORE NA-R RATS( THAN DAHL)

Dahl salt-sensitive (S) rats develop hypertension in response to a hig h-salt diet, whereas Dahl salt-resistant (R) rats do not. There is goo d evidence that the Dahl S kidneys have diminished natriuretic capacit y. We studied the rate of Na+ trans port by primary cultures of the in ner medullary collecting duct from these two strains to determine whet her there were intrinsic differences. Monolayers obtained from prehype rtensive S rats transported Na+ at twice the rate as monolayers from a ge-matched R rats. Mineralocorticoid and glucocorticoid hormones incre ased Na+ transport from both strains; the S rat monolayers always disp layed higher transport rates than R rat monolayers with the same treat ment. The Na+ entry pathway in both S and R rat monolayers was via an Na+ channel. The difference in Na+ transport was not explained by a di fference in the metabolism of corticosterone, ATP content, citrate syn thase activity, ultrastructural appearance, or rate of maturation. Mon olayers from S rats tended to have higher protein and DNA content, but these differences could not account for the difference in Na+ transpo rt. Anion secretion in response to adenosine 3',5'-cyclic monophosphat e agonists was similar. These results demonstrate intrinsic difference s in renal tubular cells that may play an important role in the pathog enesis of salt-sensitive hypertension.