Reciprocal regulation of K+ channels by Ca2+ in intact human T lymphocytes. Recept Channels 1993;1(3):201-15
Date
01/01/1993Pubmed ID
7922020Scopus ID
2-s2.0-0027135847 18 CitationsAbstract
The requirement for increased [Ca2+]i during T cell activation is well established. In the present study, we have used the cell-attached configuration of the patch-clamp technique and Ca2+ spectrofluorometry to investigate the regulation of K+ channel activity by intracellular calcium [Ca2+]i in intact human T lymphocytes. The predominant ion current in resting human T cells is a voltage-dependent K+ current, K(V), which is susceptible to second-messenger regulation. We report here that K(V) channel activity is reversibly inhibited at all relevant membrane potentials by a rise in [Ca2+]i induced by Ca2+ ionophore or the mitogens, concanavalin A or phytohemagglutinin. Consistent with this Ca2+ dependence, lowering [Ca2+]i with Ca(2+)-depleted medium can induce K(V) channel activity in otherwise quiet patches. We have also found two Ca(2+)-activated K+ channels (K(Ca)), a 9 pS channel and an inwardly rectifying 11-25 pS channel, similar to those we found in rat thymic T cells and human B cells. The sensitivity of these K(Ca) channels to [Ca2+]i suggests reciprocal regulation with that of K(V) channels. A considerable lag between mitogen treatment and induction of 9 pS K(Ca) activity, the decrease in this channel's activity in the continued presence of high [Ca2+]i or upon patch excision, and the decreased sensitivity of K(V) to Ca2+i block in disrupted cells all argue for the involvement of intracellular factors. During [Ca2+]i-mediated inhibition of K(V) channels, the recruitment of distinct K(Ca) channels is likely to play a central role in maintaining cell hyperpolarization and a sustained driving force for Ca2+ influx during T-cell activation.
Author List
Schlichter LC, Pahapill PA, Schumacher PAAuthor
Peter A. Pahapill MD, PhD Associate Professor in the Neurosurgery department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Action PotentialsCalcium
Concanavalin A
Electric Conductivity
Humans
In Vitro Techniques
Intracellular Fluid
Ionomycin
Membrane Potentials
Phytohemagglutinins
Potassium Channels
T-Lymphocytes
