Shen X, Bhargava V, Wodicka G R, Doerschuk C M, Gunst S J, Tepper R S
Department of Pediatrics, Indian University School of Medicine, Indianapolis 46223, USA.
J Appl Physiol (1985). 1996 Dec;81(6):2637-43. doi: 10.1152/jappl.1996.81.6.2637.
It has been demonstrated that methacholine (MCh) challenge produces a greater increase in lung resistance in immature than in mature rabbits (R. S. Tepper, X. Shen, E. Bakan, and S. J. Gunst. J. Appl. Physiol. 79: 1190-1198, 1995). To determine whether this maturational difference in the response to MCh was primarily related to changes in airway resistance (Raw) or changes in tissue resistance, we assessed airway narrowing in 1-, 2-, and 6-mo-old rabbits during intravenous MCh challenge (0.01-5.0 mg/kg). Airway narrowing was determined from measurements of Raw in vivo and from morphometric measurements on lung sections obtained after rapidly freezing the lung after the MCh challenge. The fold increase in Raw was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. Similarly, the degree of airway narrowing assessed morphometrically was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. The fold increase in Raw was highly correlated with the degree of airway narrowing assessed morphometrically (r2 = 0.82, P < 0.001). We conclude that the maturational difference in the effect of MCh on lung resistance is primarily caused by greater airway narrowing in the immature rabbits.
业已证实，与成熟兔相比，乙酰甲胆碱（MCh）激发试验在未成熟兔中引起的肺阻力增加幅度更大（R.S. 特珀、X. 沈、E. 巴坎和S.J. 冈斯特。《应用生理学杂志》79: 1190 - 1198, 1995）。为了确定对MCh反应的这种成熟差异是否主要与气道阻力（Raw）变化或组织阻力变化有关，我们评估了1月龄、2月龄和6月龄兔在静脉注射MCh激发试验（0.01 - 5.0 mg/kg）期间的气道狭窄情况。气道狭窄通过体内Raw测量以及在MCh激发试验后快速冷冻肺脏后获得的肺切片形态测量来确定。1月龄和2月龄动物的Raw增加倍数显著高于6月龄动物。同样，通过形态测量评估的气道狭窄程度在1月龄和2月龄动物中也显著高于6月龄动物。Raw增加倍数与通过形态测量评估的气道狭窄程度高度相关（r2 = 0.82, P < 0.001）。我们得出结论，MCh对肺阻力作用的成熟差异主要是由未成熟兔中更大程度的气道狭窄引起的。
