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Effects of Bretylium Tosylate on Voltage-Gated Potassium Channels in Human T Lymphocytes

Effects of Bretylium Tosylate on Voltage-Gated Potassium Channels in Human T Lymphocytes

R Gáspár Jr, G Panyi, D L Ypey, Z Krasznai, G Vereb, C Pieri, S Damjanovich

Mol Pharmacol. 1994 Oct;46(4):762-6.

PMID: 7969057

Abstract:

Using the patch-clamp technique, we determined that bretylium tosylate, a quaternary ammonium compound possessing immunomodulating activity, decreased the whole-cell K+ current in human T lymphocytes, in a dose-dependent manner, in the 0.05-5 mM extracellular concentration range. Bretylium tosylate prolonged the recovery from inactivation and accelerated the inactivation and deactivation of the K+ current but did not influence the kinetics of activation or the voltage dependence of activation and steady state inactivation of the K+ conductance. The percentage of drug-induced block was independent of membrane potential. K+ channel block by bretylium tosylate was partially and slowly removable by washing with drug-free extracellular solution. Bovine serum albumin (10 mg/ml) in the bath lifted the drug-induced block almost instantaneously, although not completely. In control experiments bovine serum albumin increased the inactivation time constant of the K+ channels but left the peak K+ current amplitude unaffected. On the basis of the experimental evidence, a gating-dependent allosteric interaction is suggested for the mechanism of drug action. The effective dose range, time of exposure, and reversibility of bretylium tosylate-induced K+ channel block correlated well with the same parameters of the drug-induced inhibition of T lymphocyte activation. The reported effects of bretylium tosylate on T cell mitogenesis can be regarded partly as a consequence of its blocking effects on voltage-gated K+ channels.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP61756	Bretylium tosylate		61-75-6	Price

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