M-current in human neocortical neurones

Intracellular recordings were made in slices of human neocortex that had been surgically excised from patients in order to remove deep lying brain tumours. In more than half the neurones studied under voltage-clamp (n = 9), a non-inactivating K+-current was detected that was turned on at potentials positive to around -60 mV. This conductance persisted when Ca2+-flux into neurones was blocked with Cd2+ and it was suppressed by muscarine (20 microM). The slow kinetics and voltage sensitivity of this K+ conductance, together with its muscarinic suppression, identified it as the M-current (IM). In addition to IM, evidence for the existence of Ca2+ and Ca2+-activated conductances was obtained in human neurones. These results validate the extrapolation of animal-derived data and identify IM as a target for cholinergic modulation in the human.

[1]  D. Prince,et al.  Microphysiology of human cerebral cortex studied in vitro , 1976, Brain Research.

[2]  Robert K. S. Wong,et al.  Human epileptic neurons studied in vitro , 1981, Brain Research.

[3]  P A Schwartzkroin,et al.  Intracellular study of human epileptic cortex: in vitro maintenance of epileptiform activity? , 1984, Science.

[4]  P. Schwindt,et al.  Properties of persistent sodium conductance and calcium conductance of layer V neurons from cat sensorimotor cortex in vitro. , 1985, Journal of neurophysiology.

[5]  Paul R. Adams,et al.  Voltage-clamp analysis of muscarinic excitation in hippocampal neurons , 1982, Brain Research.

[6]  D. Johnston,et al.  Voltage clamp discloses slow inward current in hippocampal burst-firing neurones , 1980, Nature.

[7]  D. A. Brown,et al.  Persistent slow inward calcium current in voltage‐clamped hippocampal neurones of the guinea‐pig. , 1983, The Journal of physiology.

[8]  D. A. Brown,et al.  M‐currents and other potassium currents in bullfrog sympathetic neurones , 1982, The Journal of physiology.

[9]  P. Gage,et al.  A threshold sodium current in pyramidal cells in rat hippocampus , 1985, Neuroscience Letters.

[10]  M. Segal,et al.  A Ca-dependent Cl− conductance in cultured mouse spinal neurones , 1984, Nature.

[11]  D. A. Brown,et al.  M-currents in voltage-clamped mammalian sympathetic neurones , 1981, Neuroscience Letters.

[12]  A SLOW, MUSCARINE-SENSITIVE CA-DEPENDENT-K CURRENT IN GUINEA-PIG OLFACTORY CORTEX NEURONS INVITRO , 1985 .

[13]  D. A. Brown,et al.  Calcium‐activated outward current in voltage‐clamped hippocampal neurones of the guinea‐pig. , 1983, The Journal of physiology.

[14]  D. A. Brown,et al.  Muscarinic suppression of a novel voltage-sensitive K+ current in a vertebrate neurone , 1980, Nature.

[15]  J. Roll,et al.  Response to pressure and vibration of slowly adapting cutaneous mechanoreceptors in the human foot , 1982, Neuroscience Letters.

[16]  A. Constanti,et al.  M-current in voltage-clamped olfactory cortex neurones , 1983, Neuroscience Letters.