Interaction between the sugar and amino-acid transport systems at the small intestinal brush border: A comparative study

Sodium, phosphate, glucose, bicarbonate, and alanine interactions in the isolated proximal convoluted tubule of the rabbit kidney.

“…As shown in Fig. 3, the lumen-tobath flux of phosphate averaged 4.77+0.82 pmol/ mm min during perfusion with fluid containing 6.38 mM glucose and increased to 9.11±+ 1.81 pmol/mm * min in the presence of phlorizin, 10 AM, in the lumen (P < 0.02). For these same tubules in the absence of glucose in the perfusate, Jlb 4 averaged 9.70±1.72 pmol/ mm-min and was unchanged at 9.70±1.52 upon the addition ofphlorizin.…”

“…Although it is not clear how the transport of solutes as chemically different as glucose and phosphate or glucose and amino acids may interrelate, data obtained largely from intestinal transport systems have led to three basic theories. First, the various transport processes involved in the movement ofthese solutes may compete directly for limited available metabolic energy (9,10). Second, the involved solutes may be transported by a single polyfunctional carrier having kinetic characteristics that are altered by interactions with different solutes (10).…”

“…First, the various transport processes involved in the movement ofthese solutes may compete directly for limited available metabolic energy (9,10). Second, the involved solutes may be transported by a single polyfunctional carrier having kinetic characteristics that are altered by interactions with different solutes (10). Third, the interacting transport systems may be mutually affected by some consequence of a dominant transport event such as sodium movement (11)(12)(13)(14).…”

Alterations and Reversibility of the Effects of Gossypol Acetic Acid on the Intestinal Uptake of End Product Nutrients in Normal and Protein Calorie-Malnourished Male Rats

“…Na+ ions were isoosmotically replaced by choline chloridecontaining buffer. The apparent K, values were found to be the same, 8.69 in all the groups, whether normal. PCM-or gossypoltreated (1-8) when Na+ was absent and 4.17 in the presence of N a\ However, table 5 showed that there was a considerable de crease in the apparent Jmax values in normal and PCM animals by gossypol treatment while PCM per se increased the Jmax.…”

“…At the end of the incubation period, the rings were removed from the incubation medium, repeatedly washed, gently blotted and weighed. They were digested in 20% KOH [8] dissolved in a dioxanbased scintillation cocktail. Bray's fluid [9], and the tissue radioactivity was measured in a (3-scintillation counter (Beckman Instruments).…”