Relative Renal Excretion Patterns of p-Aminohippurate (PAH) and Glomerular Substances

Abstract

Renal excretion patterns of PAH have been determined relative to the excretion patterns of glomerular substances simultaneously injected into the renal arteries of anesthetized dogs. The mean transit time of secreted PAH from the renal artery to the uretero-pelvic junction is greater by about 70 seconds than the mean transit time of glomerular substances. It is shown that this delay in the secretion of PAH can be accounted for on the basis of transient accumulation of PAH within the tubular cells. A modified model for the secretion of PAH is proposed; it is suggested that the slow process in the secretion of PAH is the transport across the tubular cell. Values have been calculated for the diffusion coefficient of the hypothetical PAH-intracellular substance complex. The values calculated suggest that the complex may be macromolecular but is not necessarily particulate in size.