Effect of body temperature on the ventilatory responses in the lizard Gallotia galloti

A new technique for recording ventilatory frequency on small lizards is described. This is based on the record of the electrical potential difference that spontaneously arises during the ventilatory cycle between an active stainless steel needle electrode, implanted on the membrane of the nasal cavity, and a reference stainless steel screw electrode implanted on the parietal bone. The nasal ventilatory signal coming from these electrodes, together with a simultaneous record of the electromyogram of intercostal muscles, was used to investigate the pulmonary ventilation of the lizard Gallotia galloti over the body temperature range 5-35 degrees C. The results suggest that the ventilation pattern of this lizard begins with a passive expiration, in which electromyographic activity is not present, followed by an active expiration and then an active inspiration, these being separated by a shorter muscular resting period. The active expiration lasts longer than the active inspiration over all the range of body temperatures studied. The ventilatory frequency increases exponentially with body temperature. The duration of the muscular activity during the ventilatory cycle, in the 10-35 degrees C range of body temperature, is approximately half the ventilatory period and decreases exponentially with body temperature at half the rate at which the ventilatory period decreases. The duration of several electromyographic events recorded during the ventilatory cycle also decreases exponentially with body temperature.