Ca(2+)-activated K+ channels in human leukemic T cells - PubMed (original) (raw)

Ca(2+)-activated K+ channels in human leukemic T cells

S Grissmer et al. J Gen Physiol. 1992 Jan.

Abstract

Using the patch-clamp technique, we have identified two types of Ca(2+)-activated K+ (K(Ca)) channels in the human leukemic T cell line. Jurkat. Substances that elevate the intracellular Ca2+ concentration ([Ca2+]i), such as ionomycin or the mitogenic lectin phytohemagglutinin (PHA), as well as whole-cell dialysis with pipette solutions containing elevated [Ca2+]i, activate a voltage-independent K+ conductance. Unlike the voltage-gated (type n) K+ channels in these cells, the majority of K(Ca) channels are insensitive to block by charybdotoxin (CTX) or 4-aminopyridine (4-AP), but are highly sensitive to block by apamin (Kd less than 1 nM). Channel activity is strongly dependent on [Ca2+]i, suggesting that multiple Ca2+ binding sites may be involved in channel opening. The Ca2+ concentration at which half of the channels are activated is 400 nM. These channels show little voltage dependence over a potential range of -100 to 0 mV and have a unitary conductance of 4-7 pS in symmetrical 170 mM K+. In the presence of 10 nM apamin, a less prevalent type of K(Ca) channel with a unitary conductance of 40-60 pS can be observed. These larger-conductance channels are sensitive to block by CTX. Pharmacological blockade of K(Ca) channels and voltage-gated type n channels inhibits oscillatory Ca2+ signaling triggered by PHA. These results suggest that K(Ca) channels play a supporting role during T cell activation by sustaining dynamic patterns of Ca2+ signaling.

PubMed Disclaimer

Cited by

Selective blockers of voltage-gated K+ channels depolarize human T lymphocytes: mechanism of the antiproliferative effect of charybdotoxin.
Leonard RJ, Garcia ML, Slaughter RS, Reuben JP. Leonard RJ, et al. Proc Natl Acad Sci U S A. 1992 Nov 1;89(21):10094-8. doi: 10.1073/pnas.89.21.10094. Proc Natl Acad Sci U S A. 1992. PMID: 1279670 Free PMC article.
Investigations on the mechanism of action of the antiproliferant and ion channel antagonist flufenamic acid.
Weiser T, Wienrich M. Weiser T, et al. Naunyn Schmiedebergs Arch Pharmacol. 1996 Mar;353(4):452-60. doi: 10.1007/BF00261443. Naunyn Schmiedebergs Arch Pharmacol. 1996. PMID: 8935713
Gating properties of single SK channels in hippocampal CA1 pyramidal neurons.
Hirschberg B, Maylie J, Adelman JP, Marrion NV. Hirschberg B, et al. Biophys J. 1999 Oct;77(4):1905-13. doi: 10.1016/S0006-3495(99)77032-3. Biophys J. 1999. PMID: 10512811 Free PMC article.
Characterization of apamin-sensitive Ca(2+)-activated potassium channels in human leukaemic T lymphocytes.
Hanselmann C, Grissmer S. Hanselmann C, et al. J Physiol. 1996 Nov 1;496 ( Pt 3)(Pt 3):627-37. doi: 10.1113/jphysiol.1996.sp021714. J Physiol. 1996. PMID: 8930831 Free PMC article.
Inhibition by SK&F 96365 of Ca2+ current, IL-2 production and activation in T lymphocytes.
Chung SC, McDonald TV, Gardner P. Chung SC, et al. Br J Pharmacol. 1994 Nov;113(3):861-8. doi: 10.1111/j.1476-5381.1994.tb17072.x. Br J Pharmacol. 1994. PMID: 7858878 Free PMC article.

References

1. J Immunol. 1987 Nov 15;139(10):3224-30 - PubMed
1. Biochim Biophys Acta. 1964 May 25;79:581-91 - PubMed
1. Science. 1988 Feb 12;239(4841 Pt 1):771-5 - PubMed
1. J Gen Physiol. 1988 Aug;92(2):145-59 - PubMed
1. J Gen Physiol. 1989 Jun;93(6):1061-74 - PubMed

Ca(2+)-activated K+ channels in human leukemic T cells - PubMed (original) (raw)