Measuring the Hypoxic and Hypercapnic Ventilatory Responses of Anolis carolinensis

When exposed to hypoxia (low O2) or hypercapnia (high CO2), animals require various physiological or behavioral changes to continue to supply adequate oxygen (O2) to their cells and to expel excess carbon dioxide (CO2) to maintain pH. With hypoxic exposure, the organism typically will either increase ventilation to increase O2 uptake or decrease metabolism to decrease O2usage. For hypercapnia, the ventilatory response usually presents as an increase in ventilation to increase CO2expulsion. Hypoxic and hypercapnic ventilatory responses are more thoroughly described for mammals than for reptiles. The Green Anole, Anolis carolinensis,is a common lizard species used in biology classrooms, but to our knowledge no studies have been done on ventilatory responses in this organism. The purpose of this study was to develop a method to measure ventilation in Anolis carolinensis, in response to changes in inspired O2and CO2 concentrations, as well as to investigate the effect of increased temperature on these ventilatory responses. Using a custom-built head-body plethysmography method modified from prior studies on small mammals and birds, the study aimed to measure VE,fR, and VT, to compare ventilatory responses to 5, 7, and 9% O2and 7 and 5% CO2. We hypothesized that ventilatory responses would differ between trials at 21°C and 31°C.The major findings from this study were that 1) fR decreasedduring hypoxia, and VEdid not change overall and 2) anole breathing patterns were continuous at normoxia, but transitioned into intermittent breathing patterns with exposure to hypoxia at 31°C, and to hypercapnia at both temperatures. The results also revealed that 3) increased body temperature intensified responses to hypoxia and hypercapnia, and 4) anoles exhibited post-hypercapnic hyperpnea. This was the first time to our knowledge that any of these finding have been recorded in Anolis carolinensis. Further studies are necessary to be able to compare the findings of this study to other anoles, or even other similarly lizards. Further studies are necessary to confirm these findings and to be able to generalize these anole patterns and responses other lizards or reptiles