This work was supported by grants from The National Natural Sciences Foundation of China (30271019) and The National Key Fundamental Researh Program(G1999012007).
The responses to rapid application of γ-aminobutyric acid (GABA) and the GABA receptor characteristics of MTXO neurosecretory cells in the eyestalks of Chinese mitten-handed crab (Eriocheir sinensis) were examined by whole-cell patch clamp. Under current clamp mode, the depolarization and hyperpolarization were evoked from the three types of neurosecretory cells in response to the GABA (0.1 mmol/L) depending on the Nernst Cl- potential. Under voltage clamp mode, the inward Cl- channel currents(IGABA) were resolved from all three types of neurosecretory cells in response to GABA (0.01~5 mmol/L). The GABA currents were activated within 1 200 ms and peaked within 800 ms. No obviously desensitization was observed during GABA application. The dose-response curve showed usual S-shape, with a just-discernible effect at 0.01 mmol/L and near-saturation at 0.5 mmol/L. The GABA currents had reversal potentials that followed Nernst Cl- potentials when [Cl-] was varied. The pharmacological results revealed that the GABA receptor of the crab neurosecretory cells was sensitive to the Cl- channel blockers picrotoxin and niflumic acid (0.5 mmol/L), insensitive to GABAA receptor antagonist bicuculline and GABAC receptor agonist cis-4-aminocrotonic acid (CACA 1 mmol/L) and trans-4-aminocrotonic (TACA 1 mmol/L).
SUN Jin-Sheng, GAO Chun-Lei, XIANG Jian-Hai. Study on The GABA Gated Channels in The Neurosecretory Cells of MTXO in The Eyestalks of Eriocheir sinensis[J]. Progress in Biochemistry and Biophysics,2003,30(1):129-133
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