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

Meis, S. and H.-C. Pape. Properties of a Ca-activated K controgenic behavior, including accomodating/nonaccomodatductance in acutely isolated pyramidal-like neurons from the rat ing spike patterns, burst firing, and rhythmic-oscillatory acbasolateral amygdaloid complex. J. Neurophysiol. 78: 1256–1262, tivity (Pape and Paré 1995; Paré et al. 1995; Rainnie et al. 1997. A calcium (Ca)-activated potassium (K) conductance 1993; Sugita et al. 1993; Washburn and Moises 1992a). was studied in large pyramidal-like neurons acutely dissociated Ca-dependent mechanisms appear to be most important from the rat basolateral amygdaloid complex. Neurons were immufor the regulation of these firing patterns. For instance, the noreactive to anti-a (913–926) , a sequence-directed antibody directed neurons are capable of producing high-threshold Ca spikes against the pore-forming a-subunit of the BKCa channel, also (Washburn and Moises 1992b), and the resulting inward termed slo. Whole cell current-voltage (I-V ) relationships obtained flux of Ca is thought to control a number of secondary on application of slow (46.7 mV/s) voltage ramps from 0110 to /100 mV were N shaped positive to 030 mV. Maximal current processes, such as a chloride conductance (Sugita et al. activation occurred at /9.8 { 2.7 (SE) mV, with a mean current 1993) and a number of K conductances (Danober and Pape density of 404.8 { 25.0 pA/pF. Substitution of extracellular Ca 1996; Driesang and Pape 1997; Lang and Paré 1996; Womwith manganese (Mn) , or with magnesium (Mg) and addition ble and Moises 1993), which, in turn, shape the form of of 5 mM ethyleneglycol-bis(b-aminoethylether)-N,N,N *,N *-tetraindividual action potentials and afterpotentials as well as acetic acid, abolished the N-shaped I-V relationship with a reducrepetitive firing patterns and synaptic responses. Moreover, tion in maximal outward current to 15.3 { 2.3% of the control stimulation of metabotropic glutamate receptors in basolatvalue. The Ca-sensitive K current component, as revealed by eral amygdaloid neurons was found to result in a membrane voltage step protocols, activated at depolarizations positive to 030 hyperpolarization, most likely due to activation of a largemV with a slow time course (time constant 430.7 { 78.6 ms). The conductance Ca-dependent K current (Holmes et al. current was reduced by 80.4 { 4.6% through 1 mM tetraethyam1996). Although the properties of Ca conductances with monium chloride and by 66.8 { 3.4% through 100 nM iberiotoxin,