[Apamin sensitive component of Ca(2+)-activated K+ current of afterhyperpolarization, IAHP, in dorsal root ganglion neurons in rat].
Whole-cell voltage clamp technique was used to record the tail current in freshly isolated dorsal root ganglion (DRG) neurons of rat with an aim to investigate whether these neurons possess an apamin sensitive component of Ca(2+)-activated K+ current, IAHP. The results are as follows: (1) the amplitudes of the tail currents increased from 9.3 +/- 2.8 pA to 64.1 +/- 3.4 pA (P < 0.001) when the depolarizing duration was increased from 1 ms to 180 ms; (2) the amplitudes of the tail current were reduced when repolarizing pulses were applied, with a reversal potential of about -63 mV; (3) the amplitude of the tail current was significantly depressed or even almost completely blocked by extracellularly applied 500 mumol/L Cd2+ or intracellularly applied 11 mmol/L EGTA; (4) the amplitudes of the tail currents were decreased by about (26.32 +/- 3.9)% (P < 0.01) after 200 nmmol/L apamin was extracellularly applied; and (5) the fast component of the tail current was sensitive to 10 mmol/L TEA while the slow component was insensitive. These results suggest that an apamin sensitive component of Ca(2+)-activated K+ current may be present in afterhyperpolarization of DRG neurons.
Chen
L M
LM
Department of Physiology, Fourth Military Medical University, Xi'an 710032.
Hu
S J
SJ
Wei
G Z
GZ
D000818:Animals; D001030:Apamin / Q000494:pharmacology*; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D005260:Female; D005727:Ganglia, Spinal / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels; D051381:Rats; D017207:Rats, Sprague-Dawley
D015221:Potassium Channels; D001030:Apamin; D011188:Potassium; D002118:Calcium