Eight pig tracheal strips were stimulated to contract with log increments of methacholine from 10 to 10 M. For each strip, the concentration-response was repeated four times in a randomized order to measure isometric force, isotonic shortening against a load corresponding to either 5 or 10 % of a reference force, and average force, stiffness, elastance and resistance over one cycle while the strip length was oscillating sinusoidally by 5 % at 0.2 Hz. For each readout, the logEC50 was calculated and compared. Isotonic shortening with a 5 % load had the lowest logEC50 (-7.13), yielding a greater sensitivity than any other contractile readout (p<0.05). It was followed by isotonic shortening with a 10 % load (-6.66), elastance (-6.46), stiffness (-6.46), resistance (-6.38), isometric force (-6.32), and average force (-6.30). Some of these differences were significant. For example, the EC50 with the average force was 44 % greater than with the elastance (p=0.001). The methacholine sensitivity is thus affected by the contractile readout being measured.

中文翻译：

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气道平滑肌在力量、缩短和僵硬方面的敏感性

用 10 至 10 M 的乙酰甲胆碱对数增量刺激八只猪气管条收缩。对于每条条，以随机顺序重复浓度-响应四次，以测量等长力、等渗缩短相对于对应于 5 或​​ 5 的负载。 10% 的参考力，以及一个周期内的平均力、刚度、弹性和阻力，同时带材长度以 0.2 Hz 的频率正弦振荡 5%。对于每个读数，计算并比较 logEC50。 5% 负荷的等渗缩短具有最低的 logEC50 (-7.13)，比任何其他收缩读数具有更高的灵敏度 (p<0.05)。接下来是等张缩短，10% 负载 (-6.66)、弹性 (-6.46)、刚度 (-6.46)、阻力 (-6.38)、等长力 (-6.32) 和平均力 (-6.30)。其中一些差异是显着的。例如，平均力的 EC50 比弹性的 EC50 大 44% (p=0.001)。因此乙酰甲胆碱敏感性受到测量的收缩读数的影响。