Sulfhydryl groups essential for the volume-sensitive release of taurine from astrocytes
Por:
Martínez A., Muñoz-Clares R.A., Guerra G., Morán J., Pasantes-Morales H.
Publicada:
1 ene 1994
Resumen:
The volume-sensitive [3H]taurine efflux from cultured astrocytes was found to be strongly inhibited by the sulfhydryl group-modifying reagent N-ethylmaleimide (NEM). This maleimide inhibited taurine efflux evoked by 50% hyposmotic solutions with an IC50 of 54 ?M. The inhibition by NEM followed pseudo-first order reaction kinetics. A double log plot of the pseudo-first order constant against NEM concentration gave a linear relationship with a slope of 1.2. The data are consistent with a simple bimolecular reaction mechanism in which one molecule of NEM reacts with one sulfhydryl group per transport unit. The membrane-impermeant maleimide derivative 5-eosin maleimide did not affect the volume-stimulated taurine efflux. The sulfhydryl-modifying mercurial reagents mersalyl and p-chloro mercuribenzenesulfonate (0.5-1 mM) increased [3H]taurine efflux under isosmotic conditions and concomitantly decreased the hyposmolarity-evoked efflux. The results demonstrate an essential requirement for sulfhydryl groups for the volume-sensitive taurine efflux. © 1994.
Filiaciones:
Martínez A.:
Institute of Cell Physiology, National University of Mexico, Mexico City, Mexico
Muñoz-Clares R.A.:
Faculty of Chemistry, National University of Mexico, Mexico City, Mexico
Guerra G.:
Institute of Cell Physiology, National University of Mexico, Mexico City, Mexico
Morán J.:
Institute of Cell Physiology, National University of Mexico, Mexico City, Mexico
Pasantes-Morales H.:
Institute of Cell Physiology, National University of Mexico, Mexico City, Mexico
|