AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 5 918-R925, Copyright © 1986 by American Physiological Society
Independent osmoregulatory control of central and systemic angiotensin II concentrations in dogs
C. Simon-Oppermann, D. A. Gray and E. Simon
In 14 dogs angiotensin (ANG II)-like immunoreactivity was analyzed in
simultaneously collected samples of cerebrospinal fluid (CSF) from the
anterior part of the third cerebral ventricle and of plasma. Plasma and CSF
ANG II were not different in euhydrated conscious dogs (29.3 +/- 2.7 and
30.8 +/- 2.8 pg X ml-1, means +/- SE). During anesthesia CSF ANG II was not
significantly altered, but plasma ANG II was more than doubled in
comparison with conscious animals. In conscious dogs 24 h of dehydration
with sodium-rich food significantly increased ANG II concentration in the
plasma (to 59.8 +/- 16.5 pg X ml-1) and CSF (to 71.8 +/- 20.1 pg X ml-1).
Subsequent rehydration by drinking caused no consistent changes in plasma
ANG II within 90 min but reduced CSF ANG II significantly. Salt loading by
infusion of 5% saline in seven conscious dogs produced a small but
consistent decrease in plasma ANG II by 20%, on average, whereas CSF ANG II
rose in five animals. The directions of changes in concentration of central
ANG II compared with plasma ANG II suggest that central endogenous ANG II
may function as a central osmoregulatory mediator independent from systemic
ANG II.
