TY - JOUR
T1 - Inhibition of ATP-activated currents by met-Enk in isolated DRG neurons of the rat
AU - Xia, Bao Lu
AU - Wu, Zi Zhen
AU - Li, Xiao
AU - Li, Qin
AU - Li, Zhi Wang
PY - 2001
Y1 - 2001
N2 - The present study aimed to explore modulation of ATP-activated currents (IATP) by met-Enk in rat DRG neurons. IATP were recorded using the whole-cell patch clamp technique. The majority of the neurons examined responded to ATP (90.0%, 45/50) with inward currents. In the 45 ATP sensitive neurons three kinds of responses to application of met-Enk were distinguished: (1) inward currents (29/45), (2) outward currents (9/45), and (3) no effect (7/45). Pretreatment with met-Enk (10-9-10-5 mol/L) suppressed IATP(10-4 mol/L) in 29 neurons responding to met-Enk with inward currents. The inhibition by met-Enk of IATP could be blocked by naloxone (10-7 mol/L) in a concentration-dependent manner. Met-Enk of 10-9, 10-8, 10-7, 10-6 and 10-5 mol/L suppressed IATP by 13.2 ± 5.4% (n = 5); 39.2 ± 8.6% (n = 8),54.1 ± 8.6% (n = 8),43.3 ± 7.9% (n = 7) and 43.1 ± 7.9% (n = 7) (mean ± MSE), respectively. A comparison of concentration - response relations of ATP with and without preapplication of met-Enk indicated that after pretreatment with met-Enk (10-7 mol/L) the curve shifted downward markedly with a decrease of 25% of the maxmum value of IATP and unchanged Kd value. The suppression of IATP by met-Enk was reversed as evidenced by intracellular dialysis of H-9 by using the repatch technique. Taken together, it is suggested that the inhibition by met-Enk of IATP is caused by activation of opiate receptor, which eventually results in phosphorylation of ATP receptor, mediated by modulation of G protein coupling and intracellular signal transduction.
AB - The present study aimed to explore modulation of ATP-activated currents (IATP) by met-Enk in rat DRG neurons. IATP were recorded using the whole-cell patch clamp technique. The majority of the neurons examined responded to ATP (90.0%, 45/50) with inward currents. In the 45 ATP sensitive neurons three kinds of responses to application of met-Enk were distinguished: (1) inward currents (29/45), (2) outward currents (9/45), and (3) no effect (7/45). Pretreatment with met-Enk (10-9-10-5 mol/L) suppressed IATP(10-4 mol/L) in 29 neurons responding to met-Enk with inward currents. The inhibition by met-Enk of IATP could be blocked by naloxone (10-7 mol/L) in a concentration-dependent manner. Met-Enk of 10-9, 10-8, 10-7, 10-6 and 10-5 mol/L suppressed IATP by 13.2 ± 5.4% (n = 5); 39.2 ± 8.6% (n = 8),54.1 ± 8.6% (n = 8),43.3 ± 7.9% (n = 7) and 43.1 ± 7.9% (n = 7) (mean ± MSE), respectively. A comparison of concentration - response relations of ATP with and without preapplication of met-Enk indicated that after pretreatment with met-Enk (10-7 mol/L) the curve shifted downward markedly with a decrease of 25% of the maxmum value of IATP and unchanged Kd value. The suppression of IATP by met-Enk was reversed as evidenced by intracellular dialysis of H-9 by using the repatch technique. Taken together, it is suggested that the inhibition by met-Enk of IATP is caused by activation of opiate receptor, which eventually results in phosphorylation of ATP receptor, mediated by modulation of G protein coupling and intracellular signal transduction.
KW - ATP-activated current
KW - DRG neuron
KW - Inhibition
KW - Met-enkephaline
KW - Rat
KW - Whole-cell patch clamp technique
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M3 - Article
C2 - 12589405
AN - SCOPUS:0042510768
SN - 0371-0874
VL - 53
SP - 205
EP - 208
JO - Acta Physiologica Sinica
JF - Acta Physiologica Sinica
IS - 3
ER -