Chronic hypoxia and chronic hypercapnia differentially regulate an NMDA-sensitive component of the acute hypercapnic ventilatory response in the cane toad (Rhinella marina).

This study addressed the hypotheses that exposure to chronic hypoxia (CH) and chronic hypercapnia (CHC) would modify the acute hypercapnic ventilatory response in the cane toad (Rhinella marina; formerly Bufo marinus or Chaunus marinus) and its regulation by NMDA-mediated processes. Cane toads were exposed to 10 days of CH (10% O(2)) or CHC (3.5% CO(2)) followed by acute in vivo hypercapnic breathing trials, conducted before and after an injection of the NMDA-receptor channel blocker, MK801 into the dorsal lymph sac.

Chronic hypoxic hypercapnia modifies in vivo and in vitro ventilatory chemoreflexes in the cane toad.

Previous studies have shown that exposure to chronic hypoxia (CH) and chronic hypercapnia (CHC) alone have opposite effects on central respiratory-related pH/CO(2) chemosensitivity in the cane toad (Bufo marinus). This study examined the effects of chronic hypoxic hypercapnia (CHH) on central pH/CO(2) chemosensitivity. Cane toads were maintained at 10% O(2) and 3.

Chronic hypoxia attenuates central respiratory-related pH/CO2 chemosensitivity in the cane toad.

This study examined the effects of chronic hypoxia (CH) and mid-brain transection on central respiratory-related pH/CO(2) chemosensitivity in cane toads (Bufo marinus). Toads were exposed to 10 days of CH (10% O(2)) following which in vitro brainstem-spinal cord preparations, with the mid-brain attached, were used to examine central pH/CO(2) chemosensitivity. A reduction in artificial cerebral spinal fluid (aCSF) pH increased fictive breathing frequency (fR) and total fictive ventilation.

Chronic hypoxia modulates NMDA-mediated regulation of the hypoxic ventilatory response in an amphibian, Bufo marinus.

This study examined whether a hypoxia-tolerant amphibian, the Cane toad, undergoes mammalian-like ventilatory acclimatisation to hypoxia (VAH) and whether chronic hypoxia (CH) alters NMDA-mediated regulation of the acute hypoxic ventilatory response (HVR). Toads were exposed to 10 days of CH (10% O2) followed by acute hypoxic breathing trials or an intra-arterial injection of NaCN. Trials were conducted before and after i.