Some physiological and motivational properties of the hypovolemic stimulus for thirst

摘要: Abstract Recent studies have demonstrated that plasma volume losses (hypovolemia) could elicit water drinking in rats the absence of intracellular dehydration or increased extracellular fluid osmolarity. The present paper investigated some physiological parameters and motivational properties hypovolemic stimulus for thirst. Subcutaneous injections a hyperoncotic colloidal solution produced hypovolemia by withdrawing isosmotic into local interstitium. Plasma protein concentration hematocrit gradually increased, decreased, following these changes were used to estimate net deficits. Significant was first observed after 4–6 per cent loss continued direct proportion increasing deficit. Treatment with more concentrated solutions larger rapid proportionate increase ad libitum intake although ingested neither restored normal nor satiated Comparable rates magnitudes also obtained when required press lever water, demonstrating elicits true state thirst rather than mere reflexive drinking.