Salerno F G, Paré P, Ludwig M S
Meakins-Christie Laboratories, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
Am J Respir Crit Care Med. 1998 Mar;157(3 Pt 1):846-52. doi: 10.1164/ajrccm.157.3.9705078.
Constricted guinea pig (GP) airways are much less sensitive to changes in transpulmonary pressure (Ptp) than are those of the rat. The object of this study was to investigate whether differences in the mechanical behavior of the lung parenchyma could explain differences between the two species in the interdependence of the airway and parenchyma. Subpleural lung strips from guinea pigs and rats were excised and suspended in an organ bath. One end of each strip was attached to a force transducer and the other to a servo-controlled lever arm that effected length (L) changes in the strip. Sinusoidal oscillations at varying frequencies and amplitudes were applied at different resting tensions. Measurements of L and resting tension (T) were recorded during baseline conditions and after acetylcholine (ACh) challenge. Elastance (E) and resistance (R) were calculated by fitting changes in T and L to the equation of motion. During sinusoidal oscillations, E and R in the two species were different in both the unconstricted and constricted states. The effect of T on E was significantly different in rats and GPs; E was less dependent on T in GPs. Insofar as E is a measure of the load against which airway smooth muscle (ASM) contracts, this difference may represent a potential mechanism to explain why constricted GP airways are less sensitive to changes in Ptp.
与大鼠相比，收缩状态的豚鼠气道对跨肺压（Ptp）变化的敏感性要低得多。本研究的目的是调查肺实质机械行为的差异是否可以解释这两个物种在气道与实质相互依存关系上的差异。从豚鼠和大鼠身上切下胸膜下肺条并悬吊于器官浴槽中。每条肺条的一端连接到力传感器，另一端连接到可控制肺条长度（L）变化的伺服控制杠杆臂。在不同的静息张力下施加不同频率和幅度的正弦振荡。在基线条件下以及乙酰胆碱（ACh）激发后记录L和静息张力（T）的测量值。通过将T和L的变化拟合到运动方程来计算弹性（E）和阻力（R）。在正弦振荡期间，在未收缩和收缩状态下，两个物种的E和R均不同。T对E的影响在大鼠和豚鼠中存在显著差异；在豚鼠中，E对T的依赖性较小。鉴于E是气道平滑肌（ASM）收缩所对抗负荷的一种度量，这种差异可能是解释收缩状态的豚鼠气道对Ptp变化不太敏感的一种潜在机制。
