Influence of epidermal growth factor (EGF) on renal transport of PAH and amino acids in amino acid loaded rats

In anaesthetized adult female rats, the influence of epidermal growth facto r (EGF) on renal transport of p-amino-hippurate (PAH), electrolytes, and am ino acids was investigated. After loading with PAH: (200 mg/100 g b.wt. iv. ), PAH excretion in EGF treated rats (8 mu g/100 g b.wt, subcutaneously for 8 days, twice daily 8 a.m. and 4 p.m.) was increased by about 20 %. Contin uous infusions of glutamine, arginine (both 50 mg/100 g b.wt. per hour), or alanine (90 mg/100 g b.wt. per hour) were followed by an increase in the f ractional excretion (FE) of the administered amino acids as well as of the other endogenous amino acids. Under load conditions (alanine, arginine or g lutamine), EGF pretreatment was followed by a stimulation of renal amino ac id reabsorption. These changes in amino acid transport were connected with a significant reduction of GFR after EGF pretreatment (0.96 +/- 0.10 vs. 0. 62 +/- 0.07 ml/min x 100 g b.wt.), with a distinct increase in sodium excre tion (2.98 +/- 0.55 vs. 4.97 +/- 0.71 mu val/100 g b.wt. x 20 min) and with a retarded normal kidney weight gain (874 +/- 18 vs. 775 +/- 32 mg/100 g b .wt.). A simultaneous PAH load reduced amino acid reabsorption as a sign of overloading of renal tubular transport capacity, but in EGF pretreated ani mals the amino acid excretion was only slightly increased under these condi tions.