Kimura I, Katoh H, Kimura M
Jpn J Pharmacol. 1983 Dec;33(6):1271-8. doi: 10.1254/jjp.33.1271.
Ca spike suppressions induced by isoproterenol (IsP) and a beta 2-agonist, 5-hydroxymethyl-6-hydroxy-2-isopropylamino-1,2,3,4-tetrahydronaphthalene -1-ol (AA497), were investigated in the presence of butoxamine or practolol. The relaxations were isotonically recorded, and the Ca spike frequency was recorded using the single sucrose gap method. IsP-induced relaxation was not inhibited by butoxamine (Butox, 0.16 microM), but was inhibited by practolol (Prac, 0.188 microM). In 24 mM K+-Krebs' solution, AA497 caused relaxation in a lower dose range and suppressed to a small extent the Ca spike frequency in a higher dose range, as was observed for IsP-induced curves of log dose-spike frequency and log dose-relaxation. In normal K+-Krebs' solution, both IsP and AA497 greatly suppressed the Ca spike frequency. IsP (1.21 microM)-induced suppression of the Ca spike frequency was blocked by Prac (113 microM), and it was blocked by Butox (96 microM) to a greater extent. AA497-induced suppression of the spikes was not blocked by Prac (37.6 microM), but completely blocked by Butox (32 microM). These selective inhibitory effects of butoxamine on AA497-induced and IsP-induced Ca spike suppression demonstrate that in the adrenergic beta-receptor-mediated process in taenia coli, beta 2-mechanisms are more closely related to the Ca spike suppression than the beta 1-mechanisms are.
在丁氧胺或心得宁存在的情况下，研究了异丙肾上腺素（IsP）和β2-激动剂5-羟甲基-6-羟基-2-异丙氨基-1,2,3,4-四氢萘-1-醇（AA497）诱导的钙峰抑制作用。等张记录松弛情况，并使用单蔗糖间隙法记录钙峰频率。丁氧胺（0.16微摩尔）不抑制IsP诱导的松弛，但心得宁（0.188微摩尔）可抑制。在24毫摩尔钾离子-克雷布斯溶液中，AA497在较低剂量范围内引起松弛，在较高剂量范围内对钙峰频率有轻微抑制，这与IsP诱导的对数剂量-峰频率和对数剂量-松弛曲线情况相似。在正常钾离子-克雷布斯溶液中，IsP和AA497都能极大地抑制钙峰频率。心得宁（113微摩尔）可阻断IsP（1.21微摩尔）诱导的钙峰频率抑制，丁氧胺（96微摩尔）对其阻断作用更强。AA497诱导的峰抑制不受心得宁（37.6微摩尔）阻断，但完全被丁氧胺（32微摩尔）阻断。丁氧胺对AA497诱导和IsP诱导的钙峰抑制的这些选择性抑制作用表明，在结肠带肾上腺素能β受体介导的过程中，β2机制比β1机制与钙峰抑制的关系更密切。
