TY - JOUR
T1 - Relationships between Intracellular Calcium and Afterhyperpolarizations in Neocortical Pyramidal Neurons
AU - Abel, H. J.
AU - Lee, J. C.F.
AU - Callaway, J. C.
AU - Foehring, R. C.
PY - 2004/1
Y1 - 2004/1
N2 - We examined the effects of recent discharge activity on [Ca 2+]i in neocortical pyramidal cells. Our data confirm and extend the observation that there is a linear relationship between plateau [Ca2+]i and firing frequency in soma and proximal apical dendrites. The rise in [Ca2+] activates K+ channels underlying the afterhyperpolarization (AHP), which consists of 2 Ca 2+-dependent components: the medium AHP (mAHP) and the slow AHP (sAHP). The mAHP is blocked by apamin, indicating involvement of SK-type Ca 2+-dependent K+ channels, The identity of the apamin-insensitive sAHP SAHP channel is unknown. We compared the sAHP and the mAHP with regard to: 1) number and frequency of spikes versus AHP amplitude; 2) number and frequency of spikes versus [Ca2+]i; 3) I AHP versus [Ca2+]i. Our data suggest that sAHP channels require an elevation of [Ca2+]i in the cytoplasm, rather than at the membrane, consistent with a role for a cytoplasmic intermediate between Ca2+ and the K+ channels. The mAHP channels appear to respond to a restricted Ca2+ domain.
AB - We examined the effects of recent discharge activity on [Ca 2+]i in neocortical pyramidal cells. Our data confirm and extend the observation that there is a linear relationship between plateau [Ca2+]i and firing frequency in soma and proximal apical dendrites. The rise in [Ca2+] activates K+ channels underlying the afterhyperpolarization (AHP), which consists of 2 Ca 2+-dependent components: the medium AHP (mAHP) and the slow AHP (sAHP). The mAHP is blocked by apamin, indicating involvement of SK-type Ca 2+-dependent K+ channels, The identity of the apamin-insensitive sAHP SAHP channel is unknown. We compared the sAHP and the mAHP with regard to: 1) number and frequency of spikes versus AHP amplitude; 2) number and frequency of spikes versus [Ca2+]i; 3) I AHP versus [Ca2+]i. Our data suggest that sAHP channels require an elevation of [Ca2+]i in the cytoplasm, rather than at the membrane, consistent with a role for a cytoplasmic intermediate between Ca2+ and the K+ channels. The mAHP channels appear to respond to a restricted Ca2+ domain.
UR - http://www.scopus.com/inward/record.url?scp=0347088829&partnerID=8YFLogxK
U2 - 10.1152/jn.00583.2003
DO - 10.1152/jn.00583.2003
M3 - Article
C2 - 12917389
AN - SCOPUS:0347088829
SN - 0022-3077
VL - 91
SP - 324
EP - 335
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 1
ER -