Intestinal kinetic parameters: effects of unstirred layers and transport preparation
- 1 November 1980
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Gastrointestinal and Liver Physiology
- Vol. 239 (5), G372-G377
- https://doi.org/10.1152/ajpgi.1980.239.5.g372
Abstract
Three in vitro tissue preparations were used to derive kinetic parameters for the transport of D-glucose in rabbit jejunum and the resistance of the unstirred water layer was varied by altering the rate of stirring of the bulk phase. The apparent permeability coefficient .**GRAPHIC**. of the rabbit jejunum for D-glucose was much higher from everted sacs and full-thickness biopsies than from intestinal discs. Failure to adjust the experimentally determined flux for the contribution of the passive component led to errors in the estimation of the maximal transport rate .**GRAPHIC**. and in the apparent Michaelis constant .**GRAPHIC**. .**GRAPHIC**. was higher in biopsies than everted sacs or discs and .**GRAPHIC**. was also higher in biopsies. With each tissue preparation .**GRAPHIC**. and .**GRAPHIC**. were markedly influenced by stirring the bulk phase, whereas .**GRAPHIC**. was unchanged. Failure to account for the effect of the passive component and the unstirred layer apparently leads to major errors in the estimation of .**GRAPHIC**. .**GRAPHIC**. and .**GRAPHIC**. The magnitude of these kinetic constants is influenced by the type of in vitro system used to derive the constants and it is therefore invalid to extrapolate the results obtained using one preparation to those utilizing another preparation, or to the in vivo situation.This publication has 3 references indexed in Scilit:
- Derivation of the equations that describe the effects of unstirred water layers on the kinetic parameters of active transport processes in the intestineJournal of Theoretical Biology, 1977
- The Effect of the Unstirred Layer on Human Red Cell Water PermeabilityThe Journal of general physiology, 1967
- The use of sacs of everted small intestine for the study of the transference of substances from the mucosal to the serosal surfaceThe Journal of Physiology, 1954