Seasonal variation of hypoxic and hypercarbic ventilatory responses in the lizard Tropidurus torquatus.

Carbon dioxide (CO) and oxygen (O) influence the breathing pattern of reptiles, especially when CO is in excess or O at low concentrations and the effects of these gases on the respiratory response varies according to the species. In addition to respiratory gases, seasonal changes can also modulate breathing pattern and ventilatory responses to hypoxia and hypercarbia. Therefore, the present study investigated the breathing pattern and ventilatory responses to hypercarbia (5% CO) and hypoxia (5% O) of the Neotropical lizard Tropidurus torquatus over a period of one year, covering all seasons (summer, autumn, winter and spring).

Effect of temperature on chemosensitive locus coeruleus neurons of savannah monitor lizards, Varanus exanthematicus.

Savannah monitor lizards (Varanus exanthematicus) are unusual among ectothermic vertebrates in maintaining arterial pH nearly constant during changes in body temperature in contrast to the typical α-stat regulating strategy of most other ectotherms. Given the importance of pH in the control of ventilation, we examined the CO/H sensitivity of neurons from the locus coeruleus (LC) region of monitor lizard brainstems. Whole-cell patch-clamp electrophysiology was used to record membrane voltage in LC neurons in brainstem slices.