Dynamics of renal glucose reabsorption in rat

Summary: Glucose filtered load (FL), glomerular filtration rate (GFR) and tubular glucose reabsorption (TG) were simultaneously measured in the right, control kidney and in the left kidney with cortical necrosis (CN kidney) in rats with increasing plasma glucose concentrations (PG). Urinary glucose excretion starts when plasma concentrations (threshold value) averages 2.69 ± 0.20 mg/mL in the control kidney and 2.78 ± 0.16 mg/mL in the CN kidney (non significant; NS). For PG above the threshold value, increases in glucose FL were associated with increases in TG reabsorption. Maximal glucose reabsorption was not reached even when PG levels were 10 mg/mL. Moreover, there is a linear correlationship between TG reabsorbed and glucose FL in this range of PG. Among the two factors determining FL, our results support a linear correlationship between glucose reabsorption and GFR. Finally, no significant differences in tubular glucose reabsorption dynamics appears between control and CN kidney suggesting similar dynamics for glucose reabsorption in cortical and juxtamedullary nephrons.