Effect of aminonucleoside on transport maximum of para-aminohippurate and intrarenal blood flow distribution in rats.

The present study examined intrarenal blood flow distribution and possible involvement of tubular elements in rats with aminonucleoside (AMN)-induced nephrotic syndrome. Tubular maxima of para-aminohippurate (T M PAH) were determined during mild saline expansion in control rats and in rats on days 4, 5, 6, and 14 following a single intravenous injection of AMN (10 mg/100 gm of body weight). T M PAH and glomerular filtration rates (GFR's), unchanged from controls on day 4, were equally depressed on days 5, 6, and 14; minimum values were reached on day 6. Composite linear regression analysis of controls and AMN-treated rats showed that T M PAH and GFR's were significantly correlated (r = 0.704, p less than 0.001). Microsphere studies in animals with chronic carotid catheters demonstrated a decrease in the ratio of outer to inner cortical blood flow 6 days following AMN. The data suggest that AMN produces primarily glomerular lesions and that outer cortical blood flow is more susceptible to AMN than is inner cortical blood flow.