Meeting Abstract
P3.15 Tuesday, Jan. 6 Effects Of Ozone Exposure On The Specific Dynamic Action Of The Cane Toad, Bufo marinus JOHNSON, S.R.; MAUTZ, W.J.; DOHM, M.R.*; Chaminade University, Honolulu, HI; University of Hawaii at Hilo, Hilo, HI; Chaminade University, Honolulu, HI mdohm@chaminade.edu
Ozone (O3), a highly reactive gas, is a common air pollutant in many urban settings and in adjacent wildlife habitats. Acute O3 inhalation causes airway inflammation and decreased lung function, with effects more pronounced in exercise and other factors that elevate metabolic rate. In previous studies with amphibians and reptiles exposed to O3, we noted decreased breathing rates and reduced oxygen consumption at rest. We tested whether an acute O3 exposure (4 h) would affect specific dynamic action (SDA), the increase in metabolism associated with food processing in animals. Metabolic rates for 15 toads (mean + SD body mass at start of experiment: 108 + 31.0 g) were estimated from rates of carbon dioxide (CO2) production and oxygen (O2) consumption at 30 C by open-flow respirometry (flow rate = 100 SCCM) over seven days. After an initial 24 h period to estimate standard resting metabolic rates (SMR, mean + SD: 4.7 + 2.86 ml CO2/h), toads were force fed canned dog food (crude protein 8%, fat 3%, water 78%) approximately 10% of body weight and returned to the metabolic chamber for the next 24 h of metabolic recordings. On the third day, toads were randomly assigned to control (air) or O3 (0.8 parts per million, flow rate = 5 liters per min) for 4 h at 30 C, then returned again to metabolic chambers for an additional 5 days of metabolic recordings. Peak CO2 rates increased by a factor of 4.6 in the next 24 h and 6.1 over SMR by 48 h. Individual differences in CO2 production were significantly repeatable (P < 0.001), however, we found no significant differences between air and ozone-exposed toads in SDA (P = 0.129, split-plot rank ANCOVA). Therefore, acute exposure to O3 had little or no effect on the obligate postprandial increase in metabolism.
