The sorbitol pathway catalyzes the conversion of glucose to fructose via the intermediate sorbitol. It consists of aldose reductase (AR) and sorbitol dehydrogenase (SDH). In adult (44 day) kidney zones, AR was highest in the outer medulla. In substructures AR was highest in distal convoluted tubule. The AR was greatest in newborn and 8-day zones of developing rat kidney. Acute alloxan diabetes was associated with decreased AR in small arteries, but not glomeruli. The SDH was lowest in outer medulla. It was most active in glomeruli and distal convoluted tubules. The diabetic state leads to no change of SDH in arteries but an increase in glomeruli. SDH increased with development. This study demonstrates AR and SDH in substructures of the kidney. The pathway is present in developing kidney. In diabetes the enzymatic changes would tend to decrease accumulation of sorbitol.

Plasma norepinephrine (NE), epinephrine (EPI), dopamine (DPM), dopamine β-hydroxylase (DBH), and renin were measured in patients undergoing maintenance hemodialysis. The predialysis NE, EPI and DPM concentrations were lower than normal at 29, 7.3 and 4.8 pg/ml, respectively. The NE level increased in the erect posture to 100 pg/ml at 30 min. Levels were also measured during the postdialysis period, and were approximately the same as in normal subjects, but lower than previously published values for patients undergoing hemodialysis. In the predialysis period, NE and renin correlated upon assumption of the upright posture. It is concluded that maintenance hemodialysis can be carried out without a major distortion of the plasma catecholamine levels.