HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Robbins, J Articles by Brown, D A Search for Related Content PubMed PubMed Citation Articles by Robbins, J Articles by Brown, D A

Department of Pharmacology, University College London.

1. The M-like current IK(M,ng) in differentiated NG108-15 mouse neuroblastoma x rat glioma hybrid cells has been studied using tight-seal, whole-cell patch-clamp recording. 2. When calculated from steady-state current-voltage curves, the conductance underlying IK(M,ng) showed a Boltzmann dependence on voltage with half-activation voltage Vo = -44 mV (in 3 mM [K+]) and slope factor (a) = 8.1 mV/e-fold increase in conductance. In 12 mM [K+] Vo = -38 mV and a = 6.9 mV. The deactivation reciprocal time constant accelerated with hyperpolarization with slope factor 17 mV/e-fold voltage change. 3. The reversal potential for deactivation tail currents varied with external [K+] as if PNa/PK were 0.005. 4. Steady-state current was increased on removing external Ca2+. In the presence of external Ca2+, reactivation of IK(M, ng) after a hyperpolarizing step was delayed. This delay was preceded by an inward Ca2+ current, and coincided with an increase in intracellular [Ca2+] as measured with Indo-1 fluorescence. Elevation of intracellular [Ca2+] with caffeine also reduced IK(M, ng). 5. IK(M, ng) was inhibited by external divalent cations in decreasing order of potency (mM IC50 in parentheses): Zn2+ (0.011) greater than Cu2+ (0.018) greater than Cd2+ (0.070) greater than Ni2+ (0.44) greater than Ba2+ (0.47) greater than Fe2+ (0.69) greater than Mn2+ (0.86) greater than Co2+ (0.92) greater than Ca2+ (5.6) greater than Mg2+ (16) greater than Sr2+ (33). This was not secondary to inhibition of ICa since: (i) inhibition persisted in Ca(2+)-free solution; (ii) La3+ did not inhibit IK(M, ng) at concentrations which inhibited ICa; and (iii) organic Ca2+ channel blockers were ineffective. Inhibition comprised both depression of the maximum conductance and a positive shift of the activation curve. Addition of Ca2+ (10 microM free [Ca2+]) or Ba2+ (1 mM total [Ba2+]) to the pipette solution did not significantly change IK(M, ng). 6. IK(M, ng) was reduced by 9-amino-1,2,3,4-tetrahydroacridine (IC50 8 microM) and quinine (30 microM) but was insensitive to tetraethylammonium (IC50 greater than 30 mM), 4-aminopyridine (greater than 10 mM), apamin (greater than 3 microM) or dendrotoxin (greater than 100 nM). 7. IK(M, ng) was inhibited by bradykinin (1-10 microM) or angiotensin II (1-10 microM), but not by the following other receptor agonists: acetylcholine (10 mM), muscarine (10 microM), noradrenaline (100 microM), adrenaline (100 microM), dopamine (100 microM), histamine (100 microM), 5-hydroxytryptamine (10 microM), Met-enkephalin (1 microM), glycine (100 microM), gamma-aminobutyric acid (100 microM) or baclofen (500 microM).(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				M. Martire, P. Castaldo, M. D'Amico, P. Preziosi, L. Annunziato, and M. Taglialatela M Channels Containing KCNQ2 Subunits Modulate Norepinephrine, Aspartate, and GABA Release from Hippocampal Nerve Terminals J. Neurosci., January 21, 2004; 24(3): 592 - 597. [Abstract] [Full Text] [PDF]

				S. Diochot, E. Loret, T. Bruhn, L. Beress, and M. Lazdunski APETx1, a New Toxin from the Sea Anemone Anthopleura elegantissima, Blocks Voltage-Gated Human Ether-a-go-go-Related Gene Potassium Channels Mol. Pharmacol., July 1, 2003; 64(1): 59 - 69. [Abstract] [Full Text] [PDF]

				C. T. Simons, Y. Boucher, M. I. Carstens, and E. Carstens Lack of Quinine-evoked Activity in Rat Trigeminal Subnucleus Caudalis Chem Senses, March 1, 2003; 28(3): 253 - 259. [Abstract] [Full Text] [PDF]

				P. L. Stemkowski, F. W. Tse, V. Peuckmann, C. P. Ford, W. F. Colmers, and P. A. Smith ATP-Inhibition of M Current in Frog Sympathetic Neurons Involves Phospholipase C But Not Ins P3, Ca2+, PKC, or Ras J Neurophysiol, July 1, 2002; 88(1): 277 - 288. [Abstract] [Full Text] [PDF]

				A. A. Selyanko, J. K. Hadley, I. C. Wood, F. C. Abogadie, P. Delmas, N. J. Buckley, B. London, and D. A. Brown Two Types of K+ Channel Subunit, Erg1 and KCNQ2/3, Contribute to the M-Like Current in a Mammalian Neuronal Cell J. Neurosci., September 15, 1999; 19(18): 7742 - 7756. [Abstract] [Full Text] [PDF]

				Y. V. Korolkova, S. A. Kozlov, A. V. Lipkin, K. A. Pluzhnikov, J. K. Hadley, A. K. Filippov, D. A. Brown, K. Angelo, D. Strobak, T. Jespersen, et al. An ERG Channel Inhibitor from the Scorpion Buthus eupeus J. Biol. Chem., March 23, 2001; 276(13): 9868 - 9876. [Abstract] [Full Text] [PDF]

				A. A. Selyanko, P. Delmas, J. K. Hadley, L. Tatulian, I. C. Wood, M. Mistry, B. London, and D. A. Brown Dominant-Negative Subunits Reveal Potassium Channel Families That Contribute to M-Like Potassium Currents J. Neurosci., March 1, 2002; 22(5): RC212 - RC212. [Abstract] [Full Text] [PDF]