Hypoxic Ventilatory Depression May be Due to Central Chemoreceptor Cell Hyperpolarization
This paper concerns the possible relationship of the acid secretion found to be localized primarily over the medullary ventral surface CO2 chemosensitive regions to the phenomenon of hypoxic ventilatory depression, HVD, or “roll-off”. HVD occurs between the 5th and 25th minutes of acute steady isocapnic hypoxia in normal man at sea level, eliminating about half of the hypoxic ventilatory stimulus without reducing the slope of the CO2 response curve or central response to a constant stimulus from peripheral chemoreceptors [1–4], recovery requiring similar times . We have demonstrated hypoxic ventilatory depression (HVD) of subjects breathing ambient air, with SaO2-80–90% [6,7]. After 25 min at SpO2 = 75%, when ventilation was apparently depressed by HVD, subjects had normal or above-normal HVR (computed as the differential slope) when SpO2 was rapidly lowered from 75% to 65%.
KeywordsDepression Respiration Adenosine Pyruvate Naloxone
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