NH4+ conductance in Xenopus laevis oocytes. I. Basic observations.
Pflugers Arch
; 434(3): 306-12, 1997 Jul.
Article
en En
| MEDLINE
| ID: mdl-9178631
Current-clamp and voltage-clamp techniques were used to study the effects of NH4+ on the cell membrane conductance in Xenopus laevis oocytes. Superfusing the oocytes with NH4Cl resulted in a depolarization of the oocyte's cell membrane potential and, at a clamp potential of -70 mV, in an inward current. The magnitude of the inward current was proportional to the NH4Cl concentration in the extracellular solution and on membrane potential. The reversal potential, Erev , was -35.5 +/- 11.6 mV under control conditions and -3.1 +/- 11.0 mV (n = 19) in the presence of NH4Cl (10 mmol/l). Superfusion of the oocytes with nominally Ca2+-free solution affected the NH4Cl-evoked response only marginally. Replacement of extracellular Na+ by N-methyl-D-glucamine+ markedly reduced, but did not eliminate, the NH4Cl-sensitive current and shifted the reversal potential to more negative potentials. The NH4Cl-induced current was substantially inhibited by 0.1 mmol/l flufenamate, and was less affected by blockers of the endogenous K+ conductance, Ba2+ and isosorbiddinitrate (ISDN). The results are compatible with the activation of a conductance by NH4Cl for Na+ and NH4+. The mechanism by which NH4Cl activates the conductance remains unknown.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oocitos
/
Compuestos de Amonio Cuaternario
Límite:
Animals
Idioma:
En
Revista:
Pflugers Arch
Año:
1997
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Alemania