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Properties of a Ca 2+ -Activated K + Conductance in Acutely Isolated Pyramidal-Like Neurons From the Rat Basolateral Amygdaloid Complex

1997; American Physiological Society; Volume: 78; Issue: 3 Linguagem: Inglês

10.1152/jn.1997.78.3.1256

1522-1598

Susanne Meis, Hans‐Christian Pape,

Cardiac electrophysiology and arrhythmias

Meis, S. and H.-C. Pape. Properties of a Ca 2+ -activated K + conductance in acutely isolated pyramidal-like neurons from the rat basolateral amygdaloid complex. J. Neurophysiol. 78: 1256–1262, 1997. A calcium (Ca 2+ )-activated potassium (K + ) conductance was studied in large pyramidal-like neurons acutely dissociated from the rat basolateral amygdaloid complex. Neurons were immunoreactive to anti-α (913–926) , a sequence-directed antibody directed against the pore-forming α-subunit of the BK Ca channel, also termed slo. Whole cell current-voltage ( I-V) relationships obtained on application of slow (46.7 mV/s) voltage ramps from −110 to +100 mV were N shaped positive to −30 mV. Maximal current activation occurred at +9.8 ± 2.7 (SE) mV, with a mean current density of 404.8 ± 25.0 pA/pF. Substitution of extracellular Ca 2+ with manganese (Mn 2+ ), or with magnesium (Mg 2+ ) and addition of 5 mM ethyleneglycol-bis(β-aminoethylether)- N,N,N′,N′-tetraacetic acid, abolished the N-shaped I-V relationship with a reduction in maximal outward current to 15.3 ± 2.3% of the control value. The Ca 2+ -sensitive K + current component, as revealed by voltage step protocols, activated at depolarizations positive to −30 mV with a slow time course (time constant 430.7 ± 78.6 ms). The current was reduced by 80.4 ± 4.6% through 1 mM tetraethyammonium chloride and by 66.8 ± 3.4% through 100 nM iberiotoxin, whereas apamin up to 1 μM had no effect. It is concluded that pyramidal-like neurons of the basolateral amygdaloid complex possess BK Ca channels and the corresponding macroscopic Ca 2+ -sensitive K + conductance, activation of which will substantially contribute to the Ca 2+ -dependent regulation of electrogenic behavior in these neurons.