Nishikawa M, Suzuki S, Ikeda H, Fukuda T, Suzuki J, Okubo T
First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
J Toxicol Environ Health. 1990 Jun;30(2):123-34. doi: 10.1080/15287399009531416.
The effect of ozone dose (the product of ozone concentration and exposure time) on airway responsiveness was examined in unanesthetized, spontaneously breathing guinea pigs. Airway responsiveness was assessed by measuring specific airway resistance (sRaw) as a function of increasing concentration of inhaled methacholine (Mch) aerosol (the concentration of Mch required in order to double the baseline sRaw: PC200Mch). The airway responsiveness was measured before and at 5 min, 5 h, and 24 h after exposure. A 30-min exposure to 1 ppm ozone (dose 30 ppm.min) did not change PC200Mch at any time after exposure. Both a 90-min exposure to 1 ppm ozone and a 30-min exposure to 3 ppm ozone, which are identical in terms of ozone dose (90 ppm.min), decreased PC200Mch to a similar degree. A 120-min exposure to 3 ppm ozone (360 ppm.min) produced a much greater decrease of PC200Mch at 5 min and 5 h after exposure, compared with low-dose exposure. There was a significant correlation between ozone dose and the change in airway responsiveness. In all groups, the baseline sRaw was increased by approximately 50% at 5 min after exposure, but there was no correlation between the changes in PC200Mch and the baseline sRaw. This study suggests that ozone-induced airway hyperresponsiveness in guinea pigs is closely related to ozone dose.
在未麻醉、自主呼吸的豚鼠中，研究了臭氧剂量（臭氧浓度与暴露时间的乘积）对气道反应性的影响。通过测量特定气道阻力（sRaw）作为吸入乙酰甲胆碱（Mch）气雾剂浓度增加的函数来评估气道反应性（使基线sRaw加倍所需的Mch浓度：PC200Mch）。在暴露前以及暴露后5分钟、5小时和24小时测量气道反应性。暴露于1 ppm臭氧30分钟（剂量30 ppm·分钟）后，在任何时间PC200Mch均未改变。暴露于1 ppm臭氧90分钟和暴露于3 ppm臭氧30分钟，二者臭氧剂量相同（90 ppm·分钟），均使PC200Mch降低至相似程度。与低剂量暴露相比，暴露于3 ppm臭氧120分钟（360 ppm·分钟）在暴露后5分钟和5小时使PC200Mch下降幅度更大。臭氧剂量与气道反应性变化之间存在显著相关性。在所有组中，暴露后5分钟时基线sRaw增加约50%，但PC200Mch变化与基线sRaw之间无相关性。本研究表明，豚鼠中臭氧诱导的气道高反应性与臭氧剂量密切相关。
