Some characteristics of post-hypoxia-induced drinking in rats

When rats are returned to a normoxic environment after chronic exposure to hypoxia, they manifest a striking drinking response. Earlier studies had shown that the drinking response was an inverse linear function of the percentage of oxygen in the air to which the rats had been exposed. An objective of the present experiment was to measure the post-hypoxic drinking response at intervals during a 71-d exposure to an atmosphere containing 12% oxygen in nitrogen to assess whether the response could be observed throughout this entire period. The results suggest that the response continued unabated throughout the duration of exposure to hypoxia. The mechanism(s) accounting for the posthypoxic drinking response cannot be stated with certainty. However, the results of these studies indicate that administration of the betra-adrenoceptor antagonist, propranolol (6 mg/kg, i.p.), failed to affect the magnitude of the drink following return from hypoxia to normoxia. Hence, it is unlikely that the posthypoxic drinking response is mediated by an increase in beta-adrenergic activity.