Cardiopulmonary effects of short-term nitrogen dioxide exposure in conscious sheep

Respiratory function responses of animals and man to oxidant gases and to pulmonary emphysema

“…The most prominent functional changes are an increased respiratory frequency and reduced CO diffusing capacity, resulting from alveolar epithelial damage, edema, and hemorrhage. Johnson et al (1982) reported the same structural and functional responses in dogs exposed for 6 h to 69 ppm NO 2 , including productive cough, increased respiratory frequency, and reduced CO diffus- (Stacey et al, 1983), sheep (Abraham et al, 1980b), and guinea pigs (Murphy et al, 1964). RL = total pulmonary resistance, f = respiratory frequency, and SRAW = specific airway resistance.…”

“…Specific airway resistance was measured before and after the exposure, which included two 15 min exercise periods. Abraham et al (1980b) measured the total pulmonary resistances of 6 conscious sheep before and after exposure to 15 ppm via a head chamber. Murphy et al (1964) measured the respiratory frequencies of 10 conscious guinea pigs before and after exposure to 5.2 ppm via nose cone.…”

Pathophysiologic Responses of Sheep to Brief High-Level Nitrogen Dioxide Exposure

“…Rapid shallow breathing is a characteristic response to pulmonary irritants, including NO,. Acute constriction of the airways is not necessarily typical for this class of airborne toxins, although it has been reported for dogs, sheep (Abraham et al, 1980), and humans (Horvath, 1980) exposed to NO,. The finding that 100 ppm NO, stimulated respiration, although mild, without a noticeable R, change further characterizes NO, as a pulmonary irritant.…”

“…Although minimal effects were observed after 100 ppm NO, , this exposure cannot be construed as a "no-effect" level. Lower-level exposures, for example, 5 ppm x 1.5 hlday x 10/11 days and 15 ppm x 2-4 h, have been shown to decrease pulmonary immune responsiveness Uoel et al, 19821, and increase bronchial reactivity and decrease mucous transport rates (Abraham et al, 1980) in sheep exposed by nose-only and head-only methods, respectively. These aberrations are undoubtedly more sensitive markers of toxicity, as they occurred even though protection afforded by the nasal passages remained intact.…”

Nitrogen dioxide-induced acute lung injury in sheep

“…Fundamental differences in respiratory physiology among species (Book, 1982, Phalen, 1984 may explain the general observation that small animals appear more sensitive to NO, than large animals. Salient features of pulmonary NO, toxicity in sheep include severe hypoxemia, relatively non-compliant lungs, inflammatory cell influx, pulmonary infiltrates (Januszkiewicz et al, 1992) and increased airway responsiveness (Abraham et al, 1980b). Perhaps NO, insult in this species may have applicability as an experimental animal model for the adult respiratory distress syndrome (Bachofen et al, 1979).…”