TY - JOUR
T1 - ATP-induced inward current in neurons freshly dissociated from the tuberomammillary nucleus
AU - Furukawa, K.
AU - Ishibashi, H.
AU - Akaike, N.
PY - 1994/1/1
Y1 - 1994/1/1
N2 - 1. Neurons in the tuberomammillary nucleus (TMN), which are considered to be histaminergic, were dissociated and their response to extracellularly applied ATP was investigated in the nystatin-perforated patch recording mode under voltage-clamp condition. 2. ATP induced a sustained inward current that was slowly desensitized at a holding potential of -60 mV. 3. The ATP response increased in a concentration-dependent manner. The half-maximum concentration (EC50) was 44 μM and the Hill coefficient was 1.8. 4. The potency of ATP analogues was in the order of ATP ≥ 2-methylthio-ATP >> α,β-methylene ATP ≥ ADP. Neither adenosine nor AMP induced any response. The results suggest that the purinergic receptor in TMN neurons is P(2y). 5. The current-voltage relationship for the 100 μM ATP showed a significant inward rectification at a potential more positive than -20 mV in an external solution with 150 mM Na+, but a significant rectification current was not observed in an external solution with 150 mM Cs+. The change in the reversal potential of the ATP response (E(ATP)) to a 10-fold change of extracellular Na+ concentration was 56 mV, indicating that the ATP-induced current is highly selective for Na+ over Cl-. 6. The permeability ratio for cations was Na+:Li+:K+:Rb+:Cs+:Ca2+ = 2.16:1.36:1.68:1.54:1:2.55, indicating that the ATP-induced current is passing through the ligand-gated nonselective cation channel. 7. These results suggest that ATP has an excitatory effect on the TMN neurons by opening nonselective cation channels.
AB - 1. Neurons in the tuberomammillary nucleus (TMN), which are considered to be histaminergic, were dissociated and their response to extracellularly applied ATP was investigated in the nystatin-perforated patch recording mode under voltage-clamp condition. 2. ATP induced a sustained inward current that was slowly desensitized at a holding potential of -60 mV. 3. The ATP response increased in a concentration-dependent manner. The half-maximum concentration (EC50) was 44 μM and the Hill coefficient was 1.8. 4. The potency of ATP analogues was in the order of ATP ≥ 2-methylthio-ATP >> α,β-methylene ATP ≥ ADP. Neither adenosine nor AMP induced any response. The results suggest that the purinergic receptor in TMN neurons is P(2y). 5. The current-voltage relationship for the 100 μM ATP showed a significant inward rectification at a potential more positive than -20 mV in an external solution with 150 mM Na+, but a significant rectification current was not observed in an external solution with 150 mM Cs+. The change in the reversal potential of the ATP response (E(ATP)) to a 10-fold change of extracellular Na+ concentration was 56 mV, indicating that the ATP-induced current is highly selective for Na+ over Cl-. 6. The permeability ratio for cations was Na+:Li+:K+:Rb+:Cs+:Ca2+ = 2.16:1.36:1.68:1.54:1:2.55, indicating that the ATP-induced current is passing through the ligand-gated nonselective cation channel. 7. These results suggest that ATP has an excitatory effect on the TMN neurons by opening nonselective cation channels.
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U2 - 10.1152/jn.1994.71.3.868
DO - 10.1152/jn.1994.71.3.868
M3 - Article
C2 - 8201426
AN - SCOPUS:0028326857
VL - 71
SP - 868
EP - 873
JO - Journal of Neurophysiology
JF - Journal of Neurophysiology
SN - 0022-3077
IS - 3
ER -