Glucose handling by distal portions of the nephron during pregnancy in the rat.

Reabsorption of glucose, salt and water was measured in 7-8 day pregnant and virgin rats by micropuncturing distal nephrons during saline and glucose infusions. Unidirectional fluxes of glucose were measured in loops of Henle and collecting ducts. There were no significant differences in single nephron glomerular filtration rate (S.N.G.F.R.) between virgin and pregnant animals during saline infusion. During glucose infusion S.N.G.F.R. was higher in pregnant animals than in virgins. There is no evidence of a failure of reabsorption of glucose by the proximal tubule in pregnant animals. More glucose is reabsorbed from the loop of Henle in virgin animals than in pregnant animals during saline infusion but during glucose infusion the converse is true. During both saline and glucose infusion there is less reabsorption of glucose from the collecting duct in pregnant animals than in virgin animals. It is concluded that the increased excretion of glucose during pregnancy can be attributed to alteration of glucose handling by distal segments of the nephron.