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

摘要: Savannah monitor lizards (Varanus exanthematicus) are unusual among ectothermic vertebrates in maintaining arterial pH nearly constant during changes body temperature contrast to the typical α-stat regulating strategy of most other ectotherms. Given importance control ventilation, we examined CO2/H+ sensitivity neurons from locus coeruleus (LC) region lizard brainstems. Whole-cell patch-clamp electrophysiology was used record membrane voltage LC brainstem slices. Artificial cerebral spinal fluid equilibrated with 80% O2, 0.0-10.0% CO2, balance N2, superfused across Changes firing rate were calculated action potential recordings quantify chemosensitive response hypercapnic acidosis. Our results demonstrate that contains can be excited or inhibited by, and/or not sensitive CO2 V. exanthematicus While few activated by acidosis (15%), a higher proportion responded decreasing their exposure high at 20°C (37%); this no longer exhibited when increased 30°C. Further, changed 35°C reduction CO2-inhibited (11%) and an increase CO2-activated (35%) neurons. Expressing low may provide insights into mechanisms underlying temperature-dependent pH-stat regulatory savannah lizards.