苄阿米洛利和钌红对颈动脉窦压力感受器放电的阻断作用

Blocking Effects of Benzamil and Ruthenium Red on Carotid Baroreceptor Discharges

目的研究苄阿米洛利、阿米洛利和钌红对颈动脉窦压力感受器放电的作用,探讨压力感受器上机械敏感通道的性质。方法制备家兔离体颈动脉窦-窦神经标本,采用颈动脉窦窦内外双重灌流,钳制窦内压并记录窦神经放电,观察上述药物对压力感受器放电的作用。结果苄阿米洛利以浓度依赖性方式阻断窦神经放电,IC50值为18.5μmol/L,该阻断作用在冲洗后能大部分消除;阿米洛利(2 mmol/L)可阻断95%的窦神经放电,其作用可逆;钌红(100μmol/L)以不可逆的方式抑制89%的窦神经放电活动。结论分属A类和C类纤维的压力感受器活动均可被阿米洛利类药物和钌红阻断,提示2类压力感受纤维末梢上有相似的机械敏感通道,但是有关的机械-电转导分子还有待进一步研究。

Objective To investigate the effects of benzamil,amiloride and ruthenium red（RR） on the activity of carotid sinus baroreceptor and to probe into the properties of the mechanosensitive ion channels in arterial baroreceptor. Methods The carotid sinus nerve discharge（CSND） was recorded from rabbit carotid sinus-nerve preparations in vitro with doubly perfusing the sinus internally and externally while the intrasinus pressure was clamped.The effects of the above-mentioned chemicals on the baroreceptor discharge were investigated. Results Benzamil blocked CSND dose-dependently with IC50=18.5 μmol/L.The effect was reversible after washing out.Amiloride（2 mmol/L） inhibited the nerve activity reversibly by 95%.RR（100 μmol/L） blocked CSND irreversibly by 89%. Conclusion Benzamil,amiloride and RR could block the baroreceptor activities of both type A and type C nerve endings,implying that similar mechanosensitive ion channels might locate in the two types of receptors.However,the relevant mechano-electrical transductive molecule remains to be clarified.