Mechanism of maleic acid-induced glucosuria in dog kidney.
The multiple indicator-dilution technique in vivo and isolated brush-border membranes in vitro have been used to explore the mechanism of maleic acid-induced glucosuria in dog kidney. The interaction of D-glucose with the antiluminal membrane from the peritubular fluid surface is unaltered. It is demonstrated that alpha-methyl-D-glucoside (alpha MG) enters and exits from the proximal tubular cell only across the brush-border membrane. Then using alphaMG as a reference indicator, it is shown that maleic acid does not cause complete inhibition of D-glucose interaction with the antiluminal membrane from the cytoplasmic surface. The binding of [3H]phlorizin both in vivo and in vitro is not affected by prior administration of maleic acid, indicating that D-glucose interaction with the outside surface of the brush border is also not affected by maleic acid. The data are therefore consistent with the concept that maleic acid-induced glucosuria is due either to i) partial inhibition of D-glucose movement from cytoplasm across the antiluminal membrane into the blood, ii) stimulated movement back across the brush-border membrane into urine, or iii) a combination of the two effects.
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004285:Dogs; D005947:Glucose / Q000378:metabolism; D006029:Glycosuria / Q000139:chemically induced* / Q000378:metabolism; D007201:Indicator Dilution Techniques; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D007671:Kidney Concentrating Ability; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism; D008298:Maleates; D008358:Mannose / Q000378:metabolism; D008566:Membranes / Q000378:metabolism
D008298:Maleates; D000251:Adenosine Triphosphatases; D005947:Glucose; D008358:Mannose