Age-associated alterations in thirst and arginine vasopressin in response to a water or sodium load

Age and Ageing,  March, 1995  by Ioan Davies,  Paul A. O'Neill,  Kathleen A. McLean,  James Catania,  Derek Bennett

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Exclusion Criteria

These are grouped under three headings:

Clinical information: Detailed attention is paid to problems of the immune system: Exclusion occurs if there is evidence for infection within the preceding 6-week period, any inflammatory process, or past or present malignancy or lymphoproliferative disorders. Other conditions which may affect the immune system, including significant arteriosclerosis, cardiac insufficiency, hypertension, alcoholism and drug abuse, dementia and malnutrition (Quetelet index) are also taken into account.

Laboratory data: Exclusion occurs if the subject is outside age-dependent reference ranges for ESR, haemoglobin, mean corpuscular volume, white cell count and differential, urea, alkaline phosphatase, aspartate transaminase, glucose, protein electrophoresis and urine analysis. Abnormal chest radiograph and/or electrocardiogram also leads to exclusion.

Pharmacological interference: All subjects must be free from drugs at the time of study and must not be taking prescribed medication on a regular basis.

Appendix II

The relationship between VAS score for thirst and plasma osmolality

The equations describing the relationship between thirst and plasma osmolality for each subject are given below:

Young:

VAS = -57.18 + (Subject effect) + 0.1999 [multiply by] pOsm

(SE = 10.95) (SE = 0.03782)

Old:

VAS = -57.31 + (Subject effect) + 0.2086 [multiply by] pOsm

(SE = 14.43) (SE = 0.04996)

The relationship between plasma AVP and plasma osmolality

The equations describing the relationship between 1/AVP and plasma osmolality are reproduced below:

Young:

1/AVP = 2.302 + (Subject effect) - 0.007113 [multiply by] pOsm

(SE = 0.6830) (SE = 0.0024)

Old:

1/AVP = 2.013 + (Subject effect) - 0.00496 [multiply by] pOsm

(SE = 0.6642) (SE = 0.0023)

The relationship between VAS score for thirst and plasma osmolality

The equations describing the averaged relationships between VAS score and plasma osmolality were identical to those found for the individual subjects (i.e. without the subject effect) and are given below:

Young:

VAS = - 120.44+ 0.4178 [multiply by] pOsm

(SE = 1.66) (SE=0.09114)

Old:

VAS = -122.50 + 0.4199 [multiply by] pOsm

(SE = 1.14) (SE = 0.03846)

The relationship between plasma AVP and plasma osmolality

The relationships for each age group are set out below:

Young:

1/AVP = 3.166 - (0.00953 [multiply by] pOsm)

(SE = 0.592) (SE = 0.0019l)

Old:

1/AVP = 6.452 - (0.02041 [multiply by] pOsm)

(SE = 1.12) (SE = 0.00381)

In the young subjects the relationship accounted for a smaller amount of the variance (59%), with greater between-subject variation, whereas in the old the relationship explained 40.96% of the variance.

COPYRIGHT 1995 Oxford University Press
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