To study the association between renal renin release and the pentose pathway, we perfused nonfiltering kidneys from Sprague-Dawley rats with Krebs-Ringer bicarbonate buffer containing 5 mM glucose and 14 g/100 ml bovine serum albumin in the presence or in the absence of 0.25 mM 6-aminonicotinamide (6AN), an inhibitor of glucose-6-phosphate dehydrogenase, the rate-limiting step of the pentose pathway. Eleven kidneys perfused in the absence of 6AN had a renin secretion rate of 7.4 ± 2.2 ng ANG I·min-1· ml-1. In six kidneys perfused in the presence of 6AN, renin release was depressed to 0.56 ± 0.24 ng ANG I·min-1·ml-1. The renal renin content for four control kidneys was 56 ± 33 ng ANG I·mg-1·h-1 while in four kidneys perfused with 6AN renal renin content was lower, 35 ± 2.9 ng ANG I·mg-1·h-1. In the presence of 5 mM lactate, the renin release of eight nonfiltering kidneys was 0.31 ± 0.06 ng ANG I·min-1·ml-1. The addition of 6AN did not further depress renin secretion in the presence of lactate. 6-Aminonicotinamide also completely blocked furosemide-stimulated renin release without having any effect on glomerular filtration rate or furosemide-induced natriuresis. However, 6AN did not inhibit stimulation of renin secretion by isoproterenol. We conclude that 6-aminonicotinamide interferes with renin release by nonfiltering kidneys and also inhibits furosemide-stimulated renin release but does not affect β-adrenergic-stimulated renin secretion. Glucose but not lactate is important for maintaining augmented rates of renin secretion in nonfiltering kidneys. 6-Aminonicotinamide significantly reduced renal renin content in the presence of glucose. The present studies suggest that either nonoxidative glucose metabolism or, more likely, the pentose pathway has a role in renin secretion.
