兔离体隐动脉交感神经共同传递：电刺激的影响及α，β—亚甲基ATP的增强作用

目的：分析亚最大电压、超短时程电场刺激诱发兔离体隐动脉收缩反应的神经共同传递特征。方法：兔离体隐动脉环等长收缩测定法及电场刺激诱发交感神经源性血管收缩法。结果：电场刺激诱发隐动脉交感神经源性血管收缩反应，具有频率依赖性。α1－受体阻断剂哌唑嗪（1μmol/L）不影响2Hz电刺激诱发的血管收缩反应，对8－16Hz电刺激诱发的血管收缩反应抑制约39．9－53．8％。另一方面，以α，β-亚甲基ATP（3μmol/L）脱敏P2X1受体后，完全抑制2Hz电刺激诱发的血管收缩反应，显著增强16Hz电刺激诱发 血管收缩反应，却不影响外源性NE的累积量效曲线。联合应用哌唑嗪（1μmol/L）和α，β－亚甲基ATP（3μmol/L）完全抑制了各频率电刺激诱发的血管收缩反应。结论：2Hz电刺激亦可诱发兔离体隐动脉神经源性收缩反应，2Hz电刺激诱发的收缩反应仅与嘌呤能神经递质ATP或相关核苷酸有关。较高频率电刺激诱发的收缩反应则与ATP和NE两种递质有关。此外，α，β-亚甲基ATP使P2X1受体脱敏，并通过突触前机制增强电刺激诱发的血管收缩反应。

Sympathetic cotransmission in rabbit saphenous artery in vitro: effect of electric stimulation and potentiation by alpha,beta-methylene ATP.

AIM: To analyze the cotransmission characteristics of contractile responses to electric field stimulation with submaximal voltage and short train in the rabbit saphenous artery. METHODS: Isometric vasoconstriction of the rabbit saphenous arterial rings was recorded, and the sympathetic nerves of the arterial rings were activated with electric field stimulation. RESULTS: Electric stimulation produced contractile responses in a frequency-dependent manner in the rabbit saphenous artery. Selective alpha1-adrenoceptor antagonist, prazosin (1 micromol/L) did not affect the vasoconstriction induced by electric stimulation at 2 Hz significantly, but inhibited 39.9 % - 53.8 % of the vasoconstriction at 8 - 16 Hz. On the other hand, desensitization of the P2X1 receptor with alpha,beta-methylene ATP (3 micromol/L) abolished all the vascular responses induced by stimulation at 2 Hz, and obviously potentiated those induced by stimulation at 16 Hz, but it did not affect the concentration-dependent response curves for exogenous norepinephrine. The vasoconstriction responses induced by electric stimulation were all abolished by the treatment of a combination of prazosin (1 micromol/L) and alpha,beta-methylene ATP (3 micromol/L). CONCLUSION: The sympathetic and purinergic contractile responses can be induced by 2 Hz stimulation, and ATP is the sole transmitter causing the vasoconstriction in the rabbit saphenous artery. Contractile responses to higher frequencies are related to both norepinephrine and ATP. Desensitization of the P2X1 receptor with alpha,beta-methylene ATP potentiates the vascular responses to electric stimulation via a presynaptic mechanism.