A large, multiple-conductance chloride channel in normal human T lymphocytes. Pflugers Arch 1990 Jun;416(4):413-21
Date
06/01/1990Pubmed ID
1697943DOI
10.1007/BF00370748Scopus ID
2-s2.0-0025290825 (requires institutional sign-in at Scopus site) 58 CitationsAbstract
Chloride (Cl) channels have been proposed to play roles in lymphocyte functions including volume regulation and cellular cytotoxicity; however, direct studies of such channels in normal human lymphocytes are lacking. In the present study we describe a large conductance Cl channel observed in about 50% of excised, inside-out patches from normal human peripheral T lymphocytes. The channel has multiple conductance states with linear single-channel current-versus-voltage relationships in symmetrical Cl solutions. The most prevalent state is the largest, which has a conductance of about 365 pS. The channel closes in a voltage-dependent manner at both negative and positive potentials, but does not show voltage-dependent inactivation. The probability of opening is maximal between -15 mV and +15 mV and the voltage dependence is well described by two Boltzmann equations with half-maximal probabilities at -22.8 mV and +18.0 mV. The slopes of the voltage dependence suggest two gates in series with 5.7 and 9.6 equivalent charges. The channel was about 30 times more selective for Cl- than for Na+ or K+ under balanced osmolarity but less selective (approx. 11:1) under a large osmotic gradient. The single-channel conductance increased with Cl concentration with an apparent saturation at about 581 pS and a Michaelis-Menten constant of about 120 mM. The selectivity sequence among anions, determined from changes in reversal potential was: I- greater than NO3- greater than Br-, Cl- greater than F-, isethionate, HCO3- greater than SO4(2-) greater than gluconate, propionate greater than aspartate much greater than Na+, K+ and was apparently the same for subconductance states.(ABSTRACT TRUNCATED AT 250 WORDS)
Author List
Schlichter LC, Grygorczyk R, Pahapill PA, Grygorczyk CAuthor
Peter A. Pahapill MD, PhD Professor in the Neurosurgery department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Cell MembraneChlorides
Electric Conductivity
Humans
Ion Channels
Membrane Potentials
T-Lymphocytes