The Application of Electron Probe Microanalysis to the Study of Amino Acid Transport in the Small Intestine

Abstract

The purpose of this investigation was to explore the utilization of electron probe microanalysis for the study of solute transport by epithelial cells. Segments of small intestine from golden hamster or Amphiuma means were incubated in buffer containing 40 mM DL-selenomethionine, removed at various times between 0 and 16 min, and processed for electron probe analysis. The accumulation of the amino acid in the epithelial cells lining the intestinal specimens was assessed by measurement of X-ray intensity of Se Lα. The results suggest that selenomethionine content increased with time and reached a maximum value at approximately 4–8 min. When the experiment was repeated with 0.2 mM 2,4-dinitrophenol in the incubation medium, accumulation of selenomethionine appeared to be partially reduced. The results suggest that the probe analyses reflected an uptake process and the inhibition by 2,4-dinitrophenol suggests that at least part of this process was active transport. These preliminary observations provide evidence that electron probe microanalysis may eventually prove to be a useful tool in studying biological phenomena such as membrane transport. Difficulties encountered in tissue preparation and in attempts to repeat some of the observations, all emphasize the need for additional technical development.

This research was supported by the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health under Contract No. PH-43-66-10.