【摘要】 毁脊髓大鼠模型中,α肾上腺素受体拮抗剂酚妥拉明(phentolamine),易于拮抗外源性去甲肾上腺素(noradrenaline,NA)诱发的效应,而较难于抑制交感神经兴奋诱发的同样效应。对于交感神经兴奋诱发的心血管效应,酚妥拉明的拮抗效力则取决于电刺激的频率和刺激时程。本实验结果支持突触前α肾上腺素受体在一定条件下调节着去甲肾上腺素释放的学说。更多还原

【Abstract】 Alpha-adrenoceptor antagonist phentolamine was more effective in antagonizing responses to exogenously administrated norad-renaline than those to spinal sympathetic nerve stimulation in pithed rats. The potency of phentolamine in blocking sympathetic stimulation induced cardiovascular responses was found to depend on the stimulation frequency and duration. Phentolamine increased heart positive chrono-tropic responses at frequency of 1-4 Hz for 10 s, but not at 0.5 Hz for10 s. Phentolamine produced greater antagonism of pressor responses to spinal cord stimulation with 6 pulses at 1 - 5 Hz than that at 0.5, 10 and 20 Hz. These results support the hypothesis that presynaptic alpha-ad renoceptor modulates noradrener-gic transmission under some conditions.更多还原