A direct microfluorimetric study of organic acid passage through the proximal tubule cells of the surviving Rana temporaria frog kidney

: Accumulation of acid fluorochrome in proximal tubuli in the frog surviving kidney has been investigated. Mean concentration of fluorochrome in the tubuli is linearly related to the duration of incubation. Changes in the mean rate of transport of fluorochrome into the tubuli induced by changes in its external concentration are satisfactorily described by Michaelis-Menten equation, Michaelis constant being equal to 2.1-10(-4). Some equations are suggested which describe the kinetics of organic acid transport across basal and apical membranes of cells.