Air Quality Thresholds Research Articles

Effects of graded concentrations of cigarette smoke on plasma enzyme, corticosterone, and body temperature in rats

Male rats were exposed to cigarette smoke concentrations from 2.4 mg/m 3 of suspended particulate matter (SPM) and 8 ppm of CO to 199 mg/m 3 of SPM and 220 ppm of CO for 4 hours at rest or after light intermittent exercise. Hypothermia (37.3°C) was produced after exercise in smoke containing 15 mg/m 3 of SPM and 13 ppm of CO and its severity increased at higher smoke concentrations. Plasma lactic dehydrogenase increased significantly after exercise in smoke containing 34 mg/m 3 of SPM and 51 ppm of CO. An increase in the concentration of plasma creatine kinase and of blood glucose and in the density of PLDH isoenzyme Band 5 were found only at the highest smoke level (199 mg/m 3 of SPM and 220 ppm of CO). Plasma corticosterone concentrations were elevated after exercise in the two highest smoke concentrations. No tissue changes were found, so elevations in plasma enzymes were attributed to increased cellular permeability. Some changes induced by smoke were more severe following light exercise and were attributed to SPM at levels exceeding 34 mg/m 3 and to tissue hypoxia (COHb 11.7%) induced by Co concentrations above 51 ppm. The amount of cigarette smoke needed to induce significant systemic changes in rats greatly exceeded acceptable national air quality standards and threshold limits for SPM and CO established for man.