AJP - Renal Physiology, Vol 245, Issue 5 615-F621, Copyright © 1983 by American Physiological Society
Contribution of vasopressin to the maintenance of blood pressure during dehydration
R. L. Woods and C. I. Johnston
Normal Long-Evans rats, when dehydrated for up to 72 h, have a progressive
rise in plasma vasopressin that is associated with a fall in body weight
and urine volume, a rise in plasma and urine osmolality, and the
maintenance of normal systolic blood pressure. In contrast, Brattleboro
diabetes insipidus rats, genetically deficient in vasopressin, when
dehydrated to achieve an equivalent body weight loss, have a significant 15
mmHg fall in systolic blood pressure. Even when fluid balance is corrected
in the Brattleboro rats by the continuous administration of
1-desamino-8-D-arginine vasopressin, a synthetic vasopressin analogue with
potent antidiuretic properties but minimal pressor activity, blood pressure
still falls when the animals are dehydrated. In contrast, Brattleboro rats
infused with exogenous arginine vasopressin to produce a plasma vasopressin
level of 18.9 +/- 3.5 pg X ml-1 are able to maintain normal blood pressure
during 48 h of dehydration. This level of vasopressin is comparable to the
level found endogenously in dehydrated Long-Evans rats and is nonpressor in
normal rats. These results suggest that both the antidiuretic and
vasoconstrictor properties of vasopressin are important in the
cardiovascular response to dehydration.
