title: Differential effects of harmaline and ouabain on intestinal sodium, phenylalanine and beta-methyl-glucoside transport.
abstract: Harmaline inhibits both the Na+ -K+ -ATPase activity and the uptake of L-phenylalanine in guinea-pig intestinal mucosa. The latter effect is not a direct consequence of the former, since higher concentrations are needed to inhibit the enzyme than the influx into the mucosa; Furthermore the uptake is still sensitive to harmaline when the Na+ -K+ -ATPase has been fully inhibited by ouabain. Harmaline can inhibit L-phenylalanine influx at a concentration at which it does not affect intracellular ion concentrations. Ouabain, however, inhibits the uptake of L-phenylalanine only after a 30 min preincubation period, when the intracellular sodium concentration reached the extracellular level. Harmaline also interferes with the influx of beta-methyl-D-glucoside in the mucosa of the dog colon. Addition of harmaline at the mucosal face of the tissue suppresses all net transport of sodium and chloride ions and L-phenylalanine across the mucosa. Thus the same mode of action appears to apply in both the guinea-pig ileum and the dog colon.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D006168:Guinea Pigs; D006246:Harmaline / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology*; D010649:Phenylalanine / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D002712:Chlorides; D008757:Methylglucosides; D008759:Methylglycosides; D010649:Phenylalanine; D010042:Ouabain; D012964:Sodium; D006246:Harmaline; D000251:Adenosine Triphosphatases; D011188:Potassium