Effect of albumin infusion on renal glucose reabsorption in the rat.

Clearance and micropuncture techniques were employed to assess the relationship between renal glucose and sodium reabsorption in the rat. Late proximal tubular fluid was collected from surface nephrons before and at two intervals after the infusion of hyperoncotic albumin by a double recollection technique. Plasma glucose levels were maintained at 28-44 mM throughout. Proximal tubular reabsorptive rates for both glucose and sodium were elevated 20 min after the start of the hyperoncotic infusion. Continued infusion of the hyperoncotic albumin resulted in a natriuresis and a parallel fall in proximal glucose and sodium reabsorption. Changes in maximal glucose reabsorption rates for the whole kidney paralleled changes in glucose reabsorption in surface nephrons. The addition of calcium and magnesium to the hyperoncotic infusate diminished the natriuresis but did not alter the relationship between sodium and glucose reabsorption. These observations indicate a close relationship between proximal tubular glucose reabsorption and sodium reabsorption during hyperoncotic infusion.