Regulation of water and electrolyte metabolism during dehydration and rehydration in camels

he present study was undertaken to examine the effect of severe dehydration and rapid rehydration in electrolytes and body fluids homeostasis on the arabian camel (Camelus dromedarius), and to find out which pathway is responsible for the secretion of aldosterone in the dehydrated camel; either the renin-angiotensin axis or ACTH axis. In the first experiment ten dromedary camels were studied for a total of 29 days; 7 days under control conditions, 15 days of water deprivation and 7 days of rehydration in Bureidah (Saudi Arabia) during summer, 1996. Plasma electrolyte concentrations, plasma osmolality, packed cell volume (PCV), blood hemoglobin concentrations, plasma concentrations of glucose, creatinine, blood urea nitrogen (BUN), total protein, plasma renin activity (PRA), angiotensin II, aldosterone, arginine-vasopressin (AVP), adrenocorticotropic hormone (ACTH) and cortisol concentrations were determined during both periods. During the second trial adrenocorticotropic hormone (ACTH) and enalapril, an angiotensin-converting enzyme inhibitor (ACE-I), were utilized in two separate experiments during dehydration and control (hydration) periods. Enalapril (0.2 ;Plasma osmolality decreased significantly in both dehydrated and control camels after ACE-I administration. ACE-I induced a sharp decrease in plasma angiotensin II and aldosterone concentrations (P...