AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 5 915-R920, Copyright © 1992 by American Physiological Society
Fluid retention after oral loading with water or saline in camels
S. Benlamlih, K. Dahlborn, R. Z. Filali and J. Hossaini-Hilali
Departement de Physiologie et Therapeutique, Institut Agronomique et Veterinaire Hassan II, Rabat, Morocco.
When dehydrated camels are offered water they drink volumes of water
exceeding their body water loss during the water deprivation period. The
excess water is excreted during 2-4 days. To investigate the ability to
retain fluid in the body, normohydrated camels were loaded with water or
isotonic saline (0.1 l/kg body wt) by esophageal tube. After water loading
plasma osmolality decreased and a water diuresis was seen, but it took 3
days until the body weight returned to prehydration level. Plasma
aldosterone concentration (PAC) increased, but plasma renin activity (PRA)
and plasma atrial natriuretic peptide (ANP) concentration did not change.
After the saline loading plasma osmolality increased and total plasma
proteins and hematocrit decreased. Renal Na excretion increased 4 h after
the saline load, but the magnitude of the natriuresis was small, and the
camels had not regained their body weight 6 days after the load. PAC and
PRA decreased after saline loading, while plasma ANP concentration did not
change. These data show that camels are able to retain excess water within
the body and to tolerate blood hyposmolality for a relatively long time.
With saline the retention of fluid lasts even longer despite an attenuation
of PAC.
