Ojewole J A
Methods Find Exp Clin Pharmacol. 1983 Dec;5(10):673-84.
The responses of the rainbow lizard (Agama agama Linn.) isolated portal vein to transmural electrical stimulation and to drugs have been examined. The isolated venous muscle preparation strongly contracted in response to exogenously administered adrenaline and noradrenaline (10(-8)-2.5 x 10(-6) M) and also weakly contracted to acetylcholine and 5-hydroxytryptamine (10(-7) - 10(-5) M). The vein relaxed in response to exogenous administrations of isoprenaline (10(-8) - 2.5 x 10(-6) M) and adenosine triphosphate (ATP, 10(-7) - 10(-5) M). Transmural electrical stimulation of the isolated vein at 1-40 Hz induced frequency-dependent contractions of the venous smooth muscle which were inhibited or abolished by tetrodotoxin, alpha-adrenoceptor blockers, adrenergic neurone blocking agents, local anaesthetics, and by pretreatment of rainbow lizards with reserpine. Analysis of these findings shows that the electrical stimulation-evoked contractions of the venous blood vessel resulted from the excitation of post-ganglionic sympathetic neurones. A comparison of the relative potentiation of the venous preparation contractions induced by electrical stimulation, adrenaline and noradrenaline suggested that noradrenaline is the sympathetic transmitter mediating the contractile effects due to electrical excitation. The advantages of this preparation for studying sympathetic nerve-smooth muscle mechanisms and as a pharmacological model for investigating venous blood vessel activity are discussed.
已对彩虹蜥蜴（变色蜥）离体门静脉对透壁电刺激和药物的反应进行了研究。离体静脉肌肉制备物对外源性给予的肾上腺素和去甲肾上腺素（10⁻⁸ - 2.5×10⁻⁶ M）有强烈收缩反应，对乙酰胆碱和5-羟色胺（10⁻⁷ - 10⁻⁵ M）也有微弱收缩反应。静脉对外源性给予的异丙肾上腺素（10⁻⁸ - 2.5×10⁻⁶ M）和三磷酸腺苷（ATP，10⁻⁷ - 10⁻⁵ M）有舒张反应。以1 - 40 Hz频率对离体静脉进行透壁电刺激可诱导静脉平滑肌产生频率依赖性收缩，这种收缩被河豚毒素、α-肾上腺素受体阻滞剂、肾上腺素能神经元阻滞剂、局部麻醉剂以及用利血平预处理彩虹蜥蜴所抑制或消除。对这些发现的分析表明，静脉血管电刺激诱发的收缩是由节后交感神经元的兴奋引起的。对电刺激、肾上腺素和去甲肾上腺素诱导的静脉制备物收缩的相对增强作用的比较表明，去甲肾上腺素是介导电刺激所致收缩效应的交感神经递质。讨论了该制备物在研究交感神经-平滑肌机制以及作为研究静脉血管活性的药理学模型方面的优势。
