TY - JOUR
T1 - Calcium current activated by potassium ions in voltage-clamped rat hippocampal pyramidal neurones
AU - Deák, Ferenc
AU - Nagy, Gábor
AU - Vârnai, Péter
AU - Madarász, Emília
AU - Spät, András
PY - 1998/5/1
Y1 - 1998/5/1
N2 - 1. Neuronal activity results in local elevation of extracellular K+ concentration ([K+]0). 2. Using the patch-clamp technique in the whole-cell configuration, we investigated whether extracellular K+ activates non-voltage-operated Ca2+ channels in pyramidal cells cultured from rat embryonic hippocampi. 3. K+ (12 mM) reversibly activated a sustained inward current at a holding potential of -100 mV. Membrane conductance and variance of noise were significantly increased by K+. This current could be observed at membrane potentials negative to +60 mV. 4. Inhibitors of inward rectifier K+ channels and hyperpolarization-induced cation current reduced the current only at potentials negative to -50 mV. 5. The K+-induced current was activiated in Na+-free but not in Ca2+-free medium, did not depend on cytosolic [Cl-], and was blocked by Cd2+ but not by organic channel inhibitors. 6. Half-maximal activation of the current (at -100 mV) was attained at [K+]0 ≃ 20 mM. 7. The current is similar to I(gl), a K+-induced Ca2+ current described in glomerulosa cells. It was also present in pyramidal cells from prefrontal cortex but not in hippocampal bipolar and glial cells. 8. Activation of K+-induced Ca2+ current may elevate cytoplasmic [Ca2+] at [K+]0 levels which are insufficent to activate voltage-dependent Ca2+ channels.
AB - 1. Neuronal activity results in local elevation of extracellular K+ concentration ([K+]0). 2. Using the patch-clamp technique in the whole-cell configuration, we investigated whether extracellular K+ activates non-voltage-operated Ca2+ channels in pyramidal cells cultured from rat embryonic hippocampi. 3. K+ (12 mM) reversibly activated a sustained inward current at a holding potential of -100 mV. Membrane conductance and variance of noise were significantly increased by K+. This current could be observed at membrane potentials negative to +60 mV. 4. Inhibitors of inward rectifier K+ channels and hyperpolarization-induced cation current reduced the current only at potentials negative to -50 mV. 5. The K+-induced current was activiated in Na+-free but not in Ca2+-free medium, did not depend on cytosolic [Cl-], and was blocked by Cd2+ but not by organic channel inhibitors. 6. Half-maximal activation of the current (at -100 mV) was attained at [K+]0 ≃ 20 mM. 7. The current is similar to I(gl), a K+-induced Ca2+ current described in glomerulosa cells. It was also present in pyramidal cells from prefrontal cortex but not in hippocampal bipolar and glial cells. 8. Activation of K+-induced Ca2+ current may elevate cytoplasmic [Ca2+] at [K+]0 levels which are insufficent to activate voltage-dependent Ca2+ channels.
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U2 - 10.1111/j.1469-7793.1998.735bp.x
DO - 10.1111/j.1469-7793.1998.735bp.x
M3 - Article
C2 - 9518729
AN - SCOPUS:2642627677
SN - 0022-3751
VL - 508
SP - 735
EP - 745
JO - Journal of Physiology
JF - Journal of Physiology
IS - 3
ER -