Influence of glomerular filtration rate on renal PAH secretion rate in the rat kidney

Abstract

PAH secretion (T_PAH) was studied in rats at spontaneously occurring glomerular filtration rate (GFR). At saturated transport, T_PAH was found to be correlated to GFR. This relationship was also observed at unsaturated transport where T_PAH depends upon the PAH concentration in arterial plasma. However, no significant correlation between T_PAH and renal PAH load or renal plasma flow rate was found when the effects of GFR were removed by partial correlation analysis. A dependency of T_PAH on GFR explains the correlations found between filtration fraction (FF) and renal PAH extraction (E_PAH) or renal tubular PAH extraction fraction (E_PAH-FF_PAH). Thus, even at low PAH concentration in a. plasma, renal PAH extraction may only be assumed to be constant if the filtration fraction is constant.