N,N'-dicyclohexylcarbodiimide inactivates organic cation transport in renal brush border membranes.
The molecular mechanism of the electroneutral organic cation/H+ antiporter in renal brush border membrane vesicles was studied utilizing the prototypic organic cation N1-methylnicotinamide. The hydrophobic carbodiimide, N,N'-dicyclohexylcarbodiimide (DCCD), inactivated organic cation transport irreversibly with an IC50 of 2.6 microM at pH 7.5 and 40 nM at pH 6.0. On the other hand, the hydrophilic reagents, 1-ethyl-3-[3-(dimethylamino)-propyl]carbodiimide and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, did not affect organic cation transport. Substrate did not affect the rate of the DCCD inactivation which followed pseudo-first-order-kinetics. A double logarithmic plot of the apparent rate constants vs. the DCCD concentration gave a straight line with a slope of 0.8. The data are consistent with a simple bimolecular reaction mechanism and imply that one molecule of DCCD inactivates one carboxylate group per active transport unit and that the carboxylate group is critical for transport.
Sokol
P P
PP
Department of Pharmacology, State University of New York, Syracuse.
Holohan
P D
PD
Ross
C R
CR
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002234:Carbodiimides / Q000494:pharmacology*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000494:pharmacology; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives / Q000494:pharmacology; D011522:Protons; D011804:Quinolines / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism
D002234:Carbodiimides; D011522:Protons; D011804:Quinolines; D009536:Niacinamide; D004024:Dicyclohexylcarbodiimide; C000470:EEDQ; D012964:Sodium; D005022:Ethyldimethylaminopropyl Carbodiimide; C024058:N(1)-methylnicotinamide