GABA对小鼠回肠平滑肌自主收缩活动的影响

Effect of γ-aminobutyric acid on spontaneous contraction of ileum smooth muscle in mice

目的:观察GABA对小鼠回肠平滑肌运动功能的影响,探讨GABA的作用与β受体、NO之间的关系.方法:以离体回肠收缩张力的变化为指标,观察GABA的作用,GABAA受体抑制剂木防己苦毒素picrotoxin,β受体的阻断剂propranolol,NOS抑制剂L-NNA,cGMP合成酶的抑制剂ODQ对GABA作用的影响.结果:GABA抑制小鼠回肠平滑肌自主收缩活动.1×10-6和1×10-3mol/LGABA抑制率分别为34.71±7.35%和22.23±4.69%.picrotoxin没有改变GABA的抑制作用.L-NNA减弱GABA的抑制作用,ODQ也减弱GABA的抑制作用.NO供体L-Arg(5×10-7mol/L)使GABA(1×10-6mol/L)的抑制效应减弱,但不影响GABA(1×10-3mol/L)的抑制作用.propranolol(3×10-6mol/L)减弱GABA的抑制效应.结论:GABA对小鼠回肠自主收缩有抑制作用,这种作用可能需要cGMP和No的参与;β受体兴奋时对GABA抑制效应也有一定的影响.

AIM： To investigate the effects of γ-aminobutyric acid （GABA） on the spontaneous contraction of mouse ileac smooth muscle and the interactions between GABA and β-receptor and nitric oxide （NO）. METHODS： The contraction changes of the isolated smooth muscle stripswere recorded by tension transducer, and the change of the tension was used as the marker to evaluate the effects of GABA. The effects of ODQ, L-NNA, propranolol on the action of GABA were also analyzed.. RESULTS： GABA inhibited the spontaneous contraction of mouse ileum at the concentrations ranging from 1 × 10^-6 to 1 × 10^-3 mol/L. The contraction amplitudes were de- creased by （34.71 ± 7.35）% and （22.23 ± 4.69）%, respectively, when 1 × 10^-6 and 1 × 10^-3 mol/L GABA were used. Picrotoxin showed no significant effect on the inhibitory actions caused by GABA. The effects of GABA on the spontaneous contraction were decreased in the pres- ence of L-NNA or ODQ. L-Arg （5× 10^-7 mol/L） decreased the effect of GABA at the concentration of 1 ×10^-6 mol/L, but not at the concentration of 1 × 10^-3 mol/L. Propranolol （3 × 10^-6 mol/L） reduced the effect of GABA on the con-traction of mouse ileac smooth muscle CONCLUSION： GABA inhibits the spontaneous contraction of mouse ileac smooth muscle. This effect, which is influenced by the excitation of β-receptor may need the participation of cGMP and NO.