Endothelin-1 Induces Nitric Oxide Release Via Endothelin B Receptors In Cultured Rat Cortical Neurons

Objective: To observe the effect of endothelin (ET)-l on nitric oxide (NO) release in cultured rat cortical neurons and the ET receptor subtype(s) involved.Methods: Primary cortical neuron cultures were prepared from neonate SD rat brain and incubated for 7 days into confluence. Firstly, the cultures were stimulated with ET-1 (10 nM, 100 nM, respectively), the medium was collected at 0 min, 30 min, 6 h interval for detection of NO concentration using nitrate reductase method. Thereafter, in addition to 10 nM ET-1, BQ123 (a selective ETA receptor antagonist), BQ788 (a selective ETa receptor antagonist) or PD145065 (a non-selective ET receptor antagonist) was simultaneously added into the cultures, respectively, and the medium was collected 6 h after the administration for NO concentration measurement.Results: NO concentration in Culture medium significant increased and washigher than that in control group after treated with 10 nM ET-1 and 100 nM ET-1 for 6 h (P=0.029, 0.015, respectively), and no significant difference of NO levels in 10 nM ET-1 and 100 nM ET-1 was observed. BQ788 or PD145065, but not BQ123, completely blocked the effect of ET-1 on NO release from cultured neurons, making the NO levels in medium unchanged as compared to control (P>0.05, respectively) and obviously lower than that in ET-1 group (P<0.05, respectively).Conclusions: ET-1 can directly stimulate cultured cortex neurons to release NO via ETB receptors.