ABSTRACT
AIM: To study the effects of 3-n-butylphthalide (NBP) on the TREK-1 channel expressed in Chinese hamster ovary (CHO) cells. METHODS: Whole-cell patch-clamp recording was used to record TREK-1 channel currents. The effects of varying doses of l-NBP on TREK-1 currents were also observed. Current-clamp recordings were performed to measure the resting membrane potential in TREK-1-transfected CHO (TREK-1/CHO) and wild-type CHO (Wt/CHO) cells. RESULTS: l-NBP (0.01-10 µmol/L) showed concentration-dependent inhibition on TREK-1 currents (IC(50)=0.06±0.03 µmol/L), with a maximum current reduction of 70% at a concentration of 10 µmol/L. l-NBP showed a more potent inhibition on TREK-1 current than d-NBP or dl-NBP. This effect was partially reversed upon washout and was not voltage-dependent. l-NBP 10 µmol/L elevated the membrane potential in TREK-1/CHO cells from -55.3 mV to -42.9 mV. However, it had no effect on the membrane potential of Wt/CHO cells. CONCLUSION: 1-NBP potently inhibited TREK-1 current and elevated the membrane potential, which may contribute to its neuroprotective activity.
Subject(s)
Benzofurans/pharmacology , Membrane Potentials/drug effects , Neuroprotective Agents/pharmacology , Potassium Channels, Tandem Pore Domain/antagonists & inhibitors , Animals , Benzofurans/administration & dosage , CHO Cells , Cricetinae , Cricetulus , Dose-Response Relationship, Drug , Inhibitory Concentration 50 , Neuroprotective Agents/administration & dosage , Patch-Clamp Techniques , Rats , StereoisomerismABSTRACT
AIM: To investigate effect of ginkgo biloba extract (GBE) on N-methyl-D-aspartate (NMDA)-activated currents (I(NMDA)) and evaluate further the modulatory effects of Micro-GBE/Nano-GBE. METHODS: By means of whole-cell patch clamp technique, NMDA-activated currents from acutely isolated rat hippocampal neurons were recored. RESULTS: The majority of the neurons examined (81.8%, 90/110) were sensitive to NMDA (1 mmol/L) and its co-agonist Gly (10 micromol/L). NMDA activated an inward current, which manifested apparent desensitization and could be blocked by its specific antagonist MK-801. After the neurons were treated with Micro/Nano GBE (0.1 mg/ml) followed by the application of NMDA (1 mmol/L) and Gly (10 micromol/L) for 30 s, it was show that NMDA-activated currents were obviously inhibited (P < 0.01, n = 8). The inhibitory rate were 40% +/- 17% and 64% +/- 15% respectively. It showed that the modulatory effect of Nano-GBE (dissolved in the stander extracellular solution) on NMDA-activated current was significantly higher than that of Micro-GBE (dissolved in DMSO) (P < 0.05). CONCLUSION: The inward currents activated by NMDA could be depressed by Micro-GBE and Nano-GBE. The modulatory effects of GBE on NMDA-activated current are expected to contribute to the neuroprotective effects of ginkgo biloba extracts. In addition, at the same concentration, the modulatory effect of Nano-GBE on NMDA-activated current is better than that of Micro-GBE.
