Fluid balance in cycling rats and ovariectomized rats treated with oestradiol benzoate in physiological doses (50 ug/RAT)
1995
Khan, M.A. (Quaid-i-Azam Medical Coll., Bahawalpur (Pakistan). Physiology Dept.) | Aslam, M.
Plasma vasopressin concentrations have been shown to vary throughout the rat oestrus cycle. In order to determine how these fluctuations in vasopressin are related to fluid retention, studies have been carried out in ovariectomized female Sprague-Dawley rats injected subcutaneously daily with either vehicle or oestradiol benzoate in physiological doses (50 Mew g/rat) for 14 days. The animals were housed in individual metabolism cages under 12 hr light/12 hr dark regimen with free access to food and water. Urine samples, to determine volume, were obtained and food and water intake recorded at 8-9 and 17-18 hrs. in the oestradiol benzoate treated rats, food and water intake were reduced during both dark and light periods compared to the controls possibly due to the influence of elevated circulating oestradiol levels. Urine output showed a similar pattern of changes which appeared to be related to the vasopressin concentrations. Plasma osmolality decreased in oestradiol benzoate treated rats which was also correlated with the plasma vasopressin levels. The results of this study indicate that water retention in oestradiol benzoate treated rats and oestradiol-induced increase in vasopressin may play a role in this fluid retention.
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