The mechanism of hypercalciuria in streptozotocin-induced diabetic rats.

Metabolic studies were performed in streptozotocin-induced diabetic (D) rats and normal control (C) rats to assess the role of hyperphagia in the hypercalciuria of diabetes. Urinary calcium excretion (UCaV) was significantly higher in D v C rats fed ad libitum. When D rats were pair-fed (calorie and mineral restriction) with C rats, UCaV declined but remained significantly higher than in C rats.

Microinjection study of renal calcium absorption in the phosphate-depleted rat.

Tracer microinjection studies were performed in chronically phosphate-depleted (CPD) and phosphate-supplemented (PS) rats in order to determine the site of the defect in calcium absorption which developed in CPD. Calcium recovery in the final urine was significantly higher in CPD than in PS rats after microinjections into the early and the late proximal tubules. However, there was no significant difference in the urinary recovery between the two groups after injection into the early and late distal convoluted tubules.

Intratubular microinjection study of gentamicin transport in the rat.

The intratubular microinjection technique was used to determine the absorptive flux of radioactive gentamicin the rat. Microinjection into the early tubule and late proximal tubule resulted in recoveries of proximal 66.6 +/- 3.

Free-flow micropuncture study of renal urate transport in the Munich-Wistar rat.

In order to determine the nephron sites of urate reabsorption, the fractional rates of delivery of urate to specific segments of the superficial and deep nephrons were determined by the free-flow micropuncture technique in the Munich-Wistar rat. In nondiuretic control animals, the fractional delivery of urate to the late proximal tubule (34.1 +/- 3.

Renal handling of gentamicin by the Munich-Wistar rat.

Free-flow micropuncture studies were performed in the Munich-Wistar rat to determine the nephron sites of gentamicin transport. The rats were infused with radiolabeled gentamicin and were volume-expanded with either isotonic sodium chloride or sodium bicarbonate. The fractional delivery of ultrafilterable gentamicin (FD) out of the superficial proximal tubule averaged 75% in both groups of animals.