Abstract
Summary
The objective of these experiments was to determine whether the magnitude of the water intake measured immediately following return from hypoxia to normoxia was a function of the percentage of oxygen to which the rats had been exposed. Rats were exposed to an atmosphere containing 17.0, 16.0, 15.0 or 12.0% oxygen in nitrogen for 8 days. Food and water were available at all times both prior to and during exposure to hypoxia. Immediately following removal from hypoxia the spontaneous water intake of each rat was measured during the first, and the entire first 3 hr after removal from hypoxia. The difference in water intake between treated and control groups during both the first and the entire 3 hr after removal from hypoxia increased in a linear fashion with decreasing oxygen percentage to which the rats were previously exposed. The difference in water intakes between treated and control groups (posthypoxic thirst) measured during the first hour after removal from hypoxia reached zero at 16.5% oxygen. These results are the first to suggest that the extent of the posthypoxic thirst, and perhaps the relative dehydration induced, are inverse linear functions of the degree of hypoxia to which the rats were exposed.
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