Mechanism of drinking-induced inhibition of vasopressin secretion in dehydrated dogs

Abstract

Ingestion of water stimulates a powerful inhibitory input to secretion of arginine vasopressin (AVP) in many species. A previous study in dogs has suggested that the stimulus arises from activation of oropharyngeal receptors, but the nature of the stimulus is unknown. The objectives of this study were to determine if the taste, osmolality, or temperature of the solution ingested constituted an important element in the inhibitory mechanism and if these same attributes affected the volume ingested in response to 24 h of water deprivation in conscious dogs. Experiments consisted of a control period, a 6-min period of access to fluid, and a 60-min period after drinking, with blood samples taken frequently to assess changes in plasma AVP. Dogs were placed in a sling that allowed them to stand or lie supported with easy access to a bowl. The solutions were water at 20 and 38 degrees C; 0.9% NaCl at 20 and 38 degrees C; 1.8 and 2.7% NaCl at 20 degrees C; 5% glucose and mannitol and 10% mannitol at 20 degrees C; and liquified food at 20 degrees C. In the time-control experiment dogs were allowed to see but not drink water for 6 min.(ABSTRACT TRUNCATED AT 250 WORDS)