Sakai Y, Kwan C Y, Daniel E E
Eur J Pharmacol. 1983 Nov 25;95(3-4):161-9. doi: 10.1016/0014-2999(83)90630-1.
The influences of Tris-(hydroxymethyl)aminomethane (Tris) on the contractile responses of rat vas deferens to norepinephrine (NE), potassium chloride (KCl) and field stimulation were investigated. Equilibration of rat vas deferens muscle strips in Tris containing Tyrode medium caused a significant increase in sensitivity to KCl, but had no effect on the maximum tension induced by NE or KCl. The biphasic responses to 10(-4) M NE and 100 mM KCl, characterized by an initial fast (F) component followed by a slow (S) component, were differentially affected by Tris. The F components of NE- or KCl-induced contractions were significantly potentiated by Tris, whereas the S components of NE- or KCl-induced contractions were depressed. When the muscle strips were washed after NE- or KCl-induced contraction, the rate of relaxation reflecting the rate of loss of the sustained S-component was significantly slower in Tris-Tyrode than in Tyrode medium. In Ca2+ free medium, the F component of NE-induced contraction but not the S component was markedly potentiated by Tris. Verapamil (10(-5) M) eliminated the potentiation by Tris of the F component and further reduced the S component of the NE-induced contraction in the Tris-Tyrode medium. Both F and S components of KCl-induced contractions of rat vas deferens were sensitive to verapamil and these depressant effects were further enhanced in the presence of Tris. The contraction elicited by field stimulation was also biphasic. However, only the S component was significantly depressed by Tris and this inhibitory effect was irreversible. We conclude that Tris can exert adverse effects on the contractile properties of rat vas deferens, probably via the disturbance of Ca2+-handling by the smooth muscle membrane and possibly by affecting release of norepinephrine.
研究了三（羟甲基）氨基甲烷（Tris）对大鼠输精管对去甲肾上腺素（NE）、氯化钾（KCl）和场刺激的收缩反应的影响。将大鼠输精管肌肉条在含Tris的台氏液中平衡，可导致对KCl的敏感性显著增加，但对NE或KCl诱导的最大张力无影响。对10⁻⁴ M NE和100 mM KCl的双相反应，其特征是初始快速（F）成分后接缓慢（S）成分，受Tris的影响不同。Tris显著增强了NE或KCl诱导收缩的F成分，而NE或KCl诱导收缩的S成分则受到抑制。当在NE或KCl诱导收缩后冲洗肌肉条时，反映持续S成分丧失速率的松弛速率在Tris - 台氏液中比在台氏液中显著减慢。在无Ca²⁺培养基中，Tris显著增强了NE诱导收缩的F成分而非S成分。维拉帕米（10⁻⁵ M）消除了Tris对F成分的增强作用，并进一步降低了Tris - 台氏液中NE诱导收缩的S成分。大鼠输精管KCl诱导收缩的F和S成分均对维拉帕米敏感，且在Tris存在下这些抑制作用进一步增强。场刺激引起的收缩也是双相的。然而，只有S成分受到Tris的显著抑制，且这种抑制作用是不可逆的。我们得出结论，Tris可能通过干扰平滑肌膜对Ca²⁺的处理以及可能影响去甲肾上腺素的释放，对大鼠输精管的收缩特性产生不利影响。
