PLASMA ARGININE-VASOPRESSIN RESPONSE TO HYPERTONIC SALINE INFUSION INALZHEIMER-DISEASE

In this study, we tested the hypothesis that the plasma arginine vasop ressin (AVP) response to osmotic stimulation induced by hypertonic sal ine infusion is blunted in the early and middle stages of Alzheimer di sease (AD). Because animal data support stimulatory cholinergic mediat ion of AVP osmoregulation at a brain level, the AVP response in AD mig ht provide clinically useful information about the status of brain cho linergic systems. Seventeen AD outpatients and eight normal older subj ects underwent both a 90-min hypertonic saline infusion and a 90-min c ontrol (normal saline) infusion. Substantial increases in plasma osmol ality during hypertonic saline infusion were accompanied by substantia l and linear increases in plasma AVP in both groups. However, there we re no significant differences in AVP responses between AD and normal o lder subjects. These results do not support the utility of plasma AVP response to hypertonic saline in the assessment of brain cholinergic s tatus in AD.