Absorption through Intestinal Epithelium as Influenced by Phospholipids

Abstract

Quaternary ammonium compounds, organic cations at all physiologic pH’s, were found to be absorbed incompletely but fairly rapidly from the intestine, in vivo (Levine 1960, Levine et al. 1955). In the case of a proto-typic monoquaternary agent, benzomethamine, detailed kinetic studies showed that more than passive diffusion was involved in this absorption (Levine and Pelikan 1961). This work led to the formulation of the hypothesis that some of the quaternary compound was transferred as the neutral complex by virtue of combination with an endogenous anion. Upon testing this hypothesis, a fraction of tissue, the phosphatido-peptide fraction (Folch 1952) was found to have a significant and dose-dependent effect in increasing the degree of intestinal absorption of various quaternary ammonium compounds (Levine and Spencer 1961, Levine 1962, 1963). Kinetic studies of the absorption of benzomethamine in the presence of the phosphatido-peptide fraction have yielded data which permit the inference that the absorption of benzomethamine even in the presence of this fraction does not occur by passive (diffusion alone (Levine and Pelican 1964). The data to be reported here are results of studies undertaken to determine the mechanism by which the phosphatido-peptide fraction produces its effect on the absorption of the protottypic agent, benzomethamine.

This investigation was supported in part by research grant NB-01966 from the National Institute of Neurological Diseases and Blindness and by a Public Health Service Fellowship (for P. J. K.) Number 5-Fl-GM-19,278 from the Institute of National General Medical Sciences of the National Institutes of Health, United States Public Health Service.