Bretylium tosylate - a sodium channel opener - resulted in an increase of membrane potential of depolarized human, rat and mouse T and B lymphocytes. Flow cytometric membrane potential measurements with bis-oxonol revealed that the above hyperpolarizing effect was amiloride, ouabain, tetrodotoxin, azide and temperature sensitive. The effect showed an absolute dependence on the extracellular sodium but it was insensitive to the extracellular Ca2+ level. The voltage gating of the effect can be eliminated by either an increase of the extracellular potassium concentration or low doses of veratrin. The existence of a voltage and ligand gated sodium channel is suggested in the plasma membrane of all kinds of lymphocytes. The hyperpolarization is explained by an increased activity of the electrogenic sodium-potassium ATP-ase. Induced opening of such sodium channels may regulate the electrogenic pump activity and indirectly cell activation.
|Number of pages||4|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - May 15 1989|
ASJC Scopus subject areas
- Molecular Biology