Abstract
The objectives of this study were to use pulmonary function tests, blood gas measurements and bronchoalveolar lung lavage (BAL) to characterize lesions in the respiratory tract of young adult male Wistar rats as a result of a 5-day exposure (6 h/day) to 0, 1.1, 6.2, 15 or 26 mg n-butyl isocyanate (n-BIC)/m3 air. Further objectives were to probe the diagnostic sensitivities of these procedures in comparison with more traditional evaluations (clinical observation, lung weight, histopathology). Measurements were performed during post-exposure weeks 2 and 5. Most rats exposed to 26 mg/m3 died or were sacrificed in a moribund state during post-exposure week 2. All other rats survived the exposure regimen. In rats exposed to 15 and 26 mg/m3 a significant decrease in body weight, laboured breathing, hypoactivity, nasal discharge, cyanosis, and hypothermia were observed. Pulmonary function measurements revealed increased total lung capacity (TLC) and residual volume (RV), decreased forced expiratory flow rates and quasistatic compliance in rats exposed to 26 mg/m3. At the end of the observation period rats exposed to 6.2 and 15 mg/m3 air were hyperresponsive to an acetylcholine bronchoprovocation aerosol. Arterial blood gas measurements revealed an arterial hypoxia and an increase in venous admixture, suggesting a severe mismatch of the ventilation-perfusion relationship, Biochemical and cellular components in BAL fluid (BALF) indicated a concentration dependent and protracted increase of polymorphonuclear leucocytes and further inflammatory parameters. In the 1.1 mg/m3 group BALF parameters were not significantly elevated. The major histopathological lesions of the lung were thickening of septa, emphysema, and intra-alveolar oedema in rats exposed to 26 mg/m3. Collectively, these results demonstrate obstructive and progressive lung disease with associated gas trapping and severe disturbance of the ventilation perfusion relationship which is considered to be the cause of delayed mortality. In terms of variability and sensitivity the increase in BALF parameters was most sensitive in indicating the diseased state of the lung.
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Abbreviations
- Cdyn:
-
dynamic compliance
- Cstat:
-
quasistatic compliance
- Cspec:
-
specific compliance
- Res:
-
lung resistance
- DRes:
-
change in resistance after acetylcholine bronchoprovocation
- RV:
-
residual volume
- TLC:
-
total lung capacity
- TV:
-
tidal volume
- FVC:
-
forced vital capacity
- ERV:
-
expiratory reserve volume
- IRV:
-
inspiratory reserve volume
- FRC:
-
functional residual capacity
- MEFV:
-
maximal expiratory flow volume
- REEP:
-
resting end expiratory pressure
- Vo′:
-
maximal pulmonary volume
- K:
-
shape factor of the pressure volume curve
- PEF:
-
peak expiratory flow
- MMEF:
-
maximal mid expiratory flow
- DLCO :
-
carbon monoxide diffusing capacity
- DLCO/VA :
-
DLCO normalised to alveolar volume
- Hb:
-
haemoglobin
- HbO2 :
-
oxyhaemoglobin
- pCO2 :
-
partial pressure of arterial carbon dioxide
- pO2 :
-
partial pressure of arterial oxygen
- ApO2 :
-
alveolar pO2
- A-apO2 :
-
arterioalveolar oxygen difference
- Qs/Qt:
-
venous admixture
References
Amdur MO, Mead J (1958) Mechanics of respiration in unanesthetized guinea pigs. Am J Physiol 102: 364–368
ASTM Designation: E 981-84. Standard test method for estimating sensory irritancy of airborne chemicals. American Society for Testing and Materials, Philadelphia 19 103, USA
BCTIC Computer Code Collection - Biomedical Computing Technology Information Center: ANOVA a Fortran program to perform one-way classification analysis of variance. Vanderbilt Medical Center, Nashville, Tennessee, USA
Bergmeyer HU, Gawehn K, Grassl M (1974) Enzymes as a biochemical reagent. In: Bergmeyer HU (ed) Methods of enzymatic analysis, 2nd edn, Vol. I. Academic Press, New York, pp 425–522
Bucher JR (1987) Methyl isocyanate: a review of health effects research since Bhopal. Fundam Appl Toxicol 9: 367–379
Costa DL, Tepper JS (1988) Approaches to lung function assessment in small mammals. In: Gardner DE, Crapo JP (eds) Toxicology of the lung. Raven Press, New York, pp 147–174
Diamond L, O'Donnel M (1977) Pulmonary mechanics in normal rats. J Appl Physiol Respirat Environ Exercise Physiol 43: 942–948
Dunlap KL, Sandridge RL, Keller J (1976) Determination of isocyanates in working atmosphere by high performance liquid chromatography. Anal Chem 48: 497–499
Jones NL (1987) Blood gases and acid base physiology. G. Thieme Verlag, Stuttgart, New York
Kane LE, Barrow CS, Alarie Y (1979) A short-term test to predict acceptable levels of exposure to airborne sensory irritants. Am Ind Hyg Assoc J 40: 207–229
Likens SA, Mauderly JL (1982) Effect of elastase or histamine on singlebreath N2 washouts in the rat. J Appl Physiol Respirat Environ Exercise Physiol 52: 141–146
Naftalin L, Sexton M, Whitaker JF, Tracy D (1969) A routine procedure for estimating serum gamma-glutamyl transpeptidase activity. Clin Chem Acta 26: 293–296
Paiva M, Yernault JC, Eer de Weghe P van, Englert M (1975) A sigmoid model of the static volume-pressure curve of human lung. Respir Physiol 23: 317–323
Palecek F (1969) Measurement of ventilatory mechanics in rats. J Appl Physiol 27: 149–156
Pauluhn J (1988) Different methods used in acute and subchronic inhalation studies with potential lung irritants with particular attention to pulmonary function measurements. In: Mohr U (ed) Inhalation toxicology — the design and interpretation of inhalation studies and their use in risk assessment. Springer Verlag, Berlin, Heidelberg, New York, pp 87–101
Pauluhn J (1989) A mechanistic approach to assess the inhalation toxicity and hazard of methyl isocyanate and related aliphatic monoisocyanates. In: Mohr U (ed) Assessment of inhalation hazards. Springer Verlag, Berlin, Heidelberg, New York, pp 119–128
Pauluhn J, Machemer L, Kimmerle G (1987) Effects of inhaled cholinesterase inhibitors on bronchial tonus and on plasma and erythrocyte acetylcholinesterase in rats. Toxicology 46: 177–190
Pauluhn J, Eben A, Kimmerle G (1990) Functional, biochemical, and histopathological evidence of airway obstruction in rats following a four-hour acute inhalation exposure to n-butyl isocyanate. Exp Pathol 40: 197–202
Popov N, Schmitt M, Schilzeck S, Matthies H (1975) Eine störungsfreie Mikromethode zur Bestimmung des Proteingehaltes in Gewebehomogenaten. Acta Biol Med Germ 35: 1441–1445
Powles ACP, Jones N-L (1982) A pocket calculator program for noninvasive assessment of cardiorespiratory function. Comput Biol Med 12: 163–173
Stevens MA, Fitzgerald S, Menache MG, Costa DL, Bucher JR (1987) Functional evidence of persistent airway obstruction in rats following a two-hour inhalation exposure to methyl isocyanate. Environ Health Perspect 72: 89–94
Takezawa J, Miller FJ, O'Neil JJ (1980) Single-breath diffusing capacity and lung volumes in small laboratory mammals. J Appl Physiol Respirat Environ Exercise Physiol 48: 1052–1059
Tepper JS, Wiesert MJ, Costa DL, Watkinson WP, Weber M (1987) Cardiopulmonary effects in awake rats four and six months after exposure to methyl isocyanate. Environ Health Perspect 72: 95–103
Thorne PS, Yeske CP, Karol MH (1987) Monitoring of Guinea pig core temperature by telemetry during inhalation exposures. Fundam Appl Toxicol 9: 398–408
Troup CM, Dodd DE, Fowler EH, Frank FR (1987) Biological effects of short term high concentration exposure of methylisocyanate. II. Blood chemistry and hematologic evaluations. Environ Health Perspect 72: 21–28
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Pauluhn, J., Eben, A. Altered lung function in rats after subacute exposure to n-butyl isocyanate. Arch Toxicol 66, 118–125 (1992). https://doi.org/10.1007/BF02342505
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DOI: https://doi.org/10.1007/BF02342505