Holmberg E, Waldeck B
Acta Pharmacol Toxicol (Copenh). 1980 Feb;46(2):141-9. doi: 10.1111/j.1600-0773.1980.tb02434.x.
The soleus, a slow-contracting, and the extensor digitorum longus (EDL), a fast-contracting muscle from guinea-pig were prepared for isometric recording in vitro, and the effect of terbutaline, a beta-adrenoceptor agonist, was studied during various experimental conditions. In the soleus terbutaline caused an initial depression of the force of contraction followed by an increase. The degree of fusion of subtetanic contractions was reduced throughout the experiment. The EDL responded with an increased force only. The force of contraction of the two muscles increased with the K+-ion concentration of the medium up to 6 mM. Higher concentrations of K+ caused a depression which was partly prevented by terbutaline. When the contractions of the soleus muscle had been depressed by excess K+, depletion of K+ or by ouabain, terbutaline restored the twitch tension. It is suggested that the contractile machinery of the muscles is controlled by the ionic balance which in turn is changed following beta-adrenoceptor stimulation.
选取豚鼠的比目鱼肌（一种收缩缓慢的肌肉）和趾长伸肌（EDL，一种收缩快速的肌肉），制备用于体外等长记录的标本，并研究了β-肾上腺素能受体激动剂特布他林在各种实验条件下的作用。在比目鱼肌中，特布他林最初会导致收缩力下降，随后上升。在整个实验过程中，不完全强直收缩的融合程度降低。EDL仅表现为收缩力增加。两种肌肉的收缩力随培养基中K +离子浓度升高至6 mM而增加。更高浓度的K +会导致收缩力下降，而特布他林可部分预防这种下降。当比目鱼肌的收缩因过量K +、K +耗竭或哇巴因而受到抑制时，特布他林可恢复抽搐张力。提示肌肉的收缩机制受离子平衡控制，而离子平衡又会在β-肾上腺素能受体刺激后发生变化。
