Abrahamsen J, Nedergaard O A
Department of Pharmacology, School of Medicine, Odense University, Denmark.
Naunyn Schmiedebergs Arch Pharmacol. 1989 Mar;339(3):281-7. doi: 10.1007/BF00173578.
The purpose of this investigation was to study the effect of adrenaline on presynaptic adrenoceptors by recording the release of 3H-noradrenaline evoked by electrical-field stimulation. Adrenaline (10(-10)-3 x 10(-9) mol/l) had no effect on the 3H-overflow evoked by stimulation of aorta preloaded with 3H-noradrenaline. At 10(-8) and 3 x 10(-8) mol/l, the 3H-overflow was decreased by up to 47%. The maximum decrease was more marked in the presence of either cocaine (3 x 10(-5) mol/l) plus corticosterone (4 x 10(-5) mol/l), cocaine (3.3 x 10(-6) mol/l) plus normetanephrine (4 x 10(-5) mol/l), or desipramine (10(-6) mol/l) plus normetanephrine (10(-5) mol/l). The relationship between adrenaline-induced decrease and stimulation-frequency was dependent on the experimental design: either the decrease was the same at all frequencies (1-16 Hz) or it was more marked, the lower the frequency (1 greater than 3 greater than 8 Hz). Phentolamine and rauwolscine (both 10(-6) mol/l) antagonized the inhibitory effect of adrenaline (10(-8)-10(-6) mol/l). Phenoxybenzamine (10(-6) mol/l), prevented the inhibitory effect. No enhancing effect of adrenaline (10(-9)-10(-6) mol/l) was observed in the presence of these three alpha-adrenoceptor antagonists. Our results suggest that adrenaline activates inhibitory alpha 2-adrenoceptors, but not facilitatory beta-adrenoceptors on postganglionic sympathetic nerve terminals in rabbit aorta.
本研究的目的是通过记录电场刺激诱发的3H-去甲肾上腺素释放，来研究肾上腺素对突触前肾上腺素能受体的作用。肾上腺素（10(-10)-3×10(-9)mol/L）对预加载3H-去甲肾上腺素的主动脉刺激诱发的3H溢出无影响。在10(-8)和3×10(-8)mol/L时，3H溢出最多可降低47%。在存在可卡因（3×10(-5)mol/L）加皮质酮（4×10(-5)mol/L）、可卡因（3.3×10(-6)mol/L）加去甲变肾上腺素（4×10(-5)mol/L）或地昔帕明（10(-6)mol/L）加去甲变肾上腺素（10(-5)mol/L）的情况下，最大降幅更明显。肾上腺素诱导的降低与刺激频率之间的关系取决于实验设计：要么在所有频率（1-16Hz）下降低程度相同，要么频率越低（1＞3＞8Hz）降低越明显。酚妥拉明和萝芙木碱（均为10(-6)mol/L）拮抗肾上腺素（10(-8)-10(-6)mol/L）的抑制作用。酚苄明（10(-6)mol/L）可防止这种抑制作用。在这三种α-肾上腺素能受体拮抗剂存在的情况下，未观察到肾上腺素（10(-9)-10(-6)mol/L）的增强作用。我们的结果表明，肾上腺素激活兔主动脉节后交感神经末梢上的抑制性α2-肾上腺素能受体，但不激活促进性β-肾上腺素能受体。
