Analysis Tools
respiratory system
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• in response to hypoxia (10% O2), adult homozygotes (4-6 months of age) display a significantly reduced ventilatory response showing an increase of only 261 +/- 202 ml/min/kg in minute ventilation (VE) relative to 1008 +/- 154 ml/min/kg in wild-type controls
• in response to further hypoxia (7.5% O2), homozygotes display a severe ventilatory depression with the VE reduced below prehypoxic levels by 606 +/- 209 ml/min/kg, unlike wild-type controls where no additional increase in ventilation is observed but the VE remains above normoxic levels
• however, adult homozygotes display normal resting ventilation during normoxia and show normal ventilatory responses to a mild (15% O2) hypoxia relative to wild-type controls
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cardiovascular system
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• homozygotes show a dramatic reduction in afferent nerve responses of the carotid sinus nerve to a decrease in oxygen tension (PO2)
• unlike in in vitro carotid body-sinus nerve preparations from wild-type mice where sinus nerve discharge increases from baseline to a peak of 130.82 +/- 10.79 spikes/sec during hypoxia, the afferent discharge in preparations from mutant mice only reaches a peak of 58.13 +/- 9.40 spikes/sec, indicating that carotid body function is impaired
• the average peak firing rate of single units induced by hypoxia is significantly lower in carotid body-sinus nerve preparations from mutant mice (1.64 +/- 0.11 spikes/sec) relative to that observed in wild-type preparations (7.96 +/- 0.88 spikes/sec)
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homeostasis/metabolism
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• in response to hypoxia (7.5% O2), adult homozygotes display normal decreases in body temperature relative to wild-type controls (0.9 +/- 0.2 vs 0.8 +/- 0.1 degress Celsius, respectively)
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