The effects of a four-hour exposure (via a Plexiglas hood) to sulfur dioxide (SO 2) on airway reactivity was studied in both normal and allergic conscious sheep. Allergic sheep were defined as animals in whom inhalation of Ascaris suum extract resulted in an increase in mean pulmonary flow resistance R(L)). Airway reactivity (ΔR(L)) was assessed by measuring the increase in R(L) after 18 breaths of 0.25% carbachol, from an initial value obtained after 18 breaths of buffered saline. R(L) and ΔR(L) were determined prior to, immediately after and 24 hours following SO 2 exposure in three groups of sheep: six normal sheep exposed to 5 ppm SO 2 (group A); six normal sheep exposed to 10 ppm SO 2 (group B) and seven allergic sheep exposed to 5 ppm SO 2 (group C). R(L) was not affected by SO 2 exposure in any group but both groups B and C showed increases in ΔR(L) 24 hours after exposure. Since the increase in ΔR(L) was greater in group C than in either groups A or B, we conclude that allergic sheep have enhanced susceptibility to the injurious airway effects of SO 2.
- airway epithelium
- airway hyperreactivity
- sulfur dioxide
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health