Glycine Transport by Hemolyzed and Restored Pigeon Red Cells^*

Effect of K+ and K+ gradients on accumulation of sugars by isolated intestinal epithelial cells

“…This idea is consistent with our data indicating a modest concentration gradient of sugar can be generated by an imposed Na § gradient in DNP-treated cells. It likewise accommodates similar data derived from other cell types [17,39,40]. On the other hand, no role for K § is implied at the sugar carrier locus in agreement with the data presented in this paper.…”

“…In fact, gradients of glycine have been induced in ascites cells and red blood ceils pretreated with metabolic inhibitors by imposing inwardly directed Na + gradients [17,39,40]. Better nonelectrolyte accumulation was observed if gradients of both Na § and K + were applied [17].…”

Ionic dependence of amino-acid transport in the exocrine pancreatic epithelium: Calcium dependence of insulin action

“…5B) was not observed. The insulin-induced 45 11.7 9 0.14 a Pancreata were preperfused with an amino-acid-free solution containing either no insulin or 100/xU/ml insulin, and then perfused with 10 mM L-serine in the continued absence or presence of insulin. 1 mM ouabain was added to the respective perfusate 10 min after switching to 10 mM c-serine.…”

“…The important role of cation gradients in energizing amino-acid transport [9,12,14,21,30,33,38,41,43,45,47] together with the modulation of ionic events by insulin and its ability to induce a membrane hyperpolarization [see 1,18,30,39,47] implies a close relationship between hormonal regulation of transport [see reviews 14,38] and cation gradients. Previous studies with exocrine pancreatic fragments, acini or vesicles have identified a number of parallel amino-acid carriers differing in their substrate specificity, ionic dependency and ouabain sensitivity [4,23,29,33,43].…”

Na+-coupled glycine transport in reticulocyte vesicles of distinct sidedness: Stoichiometry and symmetry

“…Nevertheless, the orientation of most vesicle preparations has been difficult to control, so that the kinetic parameters cannot be evaluated with respect to membrane sidedness. Until now, evaluation of kinetic parameters have been carried out with either intact cells as, for example, studies of Na+-coupled glycine transport in Ehrlich ascites tumor cells (Johnstone, 1978), resealed pigeon red cells (Vidaver & Shepherd, 1968), or membrane vesicles of undefined orientation (for review see Lever, 1980). In the former studies with cells, the kinetics of Na+-dependent glycine transport appeared to be asymmetric with respect to apparent Vrnax and Km values for glycine entry and exit.…”