Syndrome of hyperosmolar hypohydration in the experiment: features of disorders of vital functions of rats with disorders of homeostasis of varying severity

Abstract

Summary. In neurosurgical patients, hypothalamic-pituitary lesions in 30 % of cases are complicated by the development of central diabetes mellitus, which is manifested by severe disorders of water-salt balance, leading to functional disorders and structural damage to organs and tissues, and can be fatal. Modeling in the experiment of hyperosmolar hypohydration, which develops in diabetes insipidus, would help to study the biochemical and pathophysiological processes that occur. The aim of the study – to simulate in the experiment the syndrome of hyperosmolar hypohydration, to investigate the peculiarities of changes in behavior, physical condition and biochemical parameters of animals depending on the level of osmolarity of blood plasma. Materials and Methods. The experiment used adult female rats (n = 62) weighing (242.0±15.0) g. To model hyperosmolar hypohydration, they were injected intraperitoneally with a solution of furosemide (5.0 mg∙kg-1), and under anesthesia with sodium thiopental (50 mg mg∙kg-1) intravenous – hypertonic (from 1.8 to 9 %) solutions of sodium chloride (2.0 ml). The rate of diuresis, urine density, calculated osmotic-volume index of urine and the degree of hypohydration of the body, physical condition and duration of anesthesia (coma), blood plasma electrolytes (Na+, K+), its osmolarity and mortality of animals depending on the severity of the simulated hyperosmolar hypohydration. Results. The experiment on rats simulated hypertensive (hyperosmolar) hypohydration of varying severity, which occurs in patients with central diabetes mellitus; the clinical and laboratory features observed in this case are reflected, and the mechanisms of the organism involved in its overcoming are studied. Conclusions. With the loss of water by experimental animals in the amount of ˃5 % of body weight, the duration of narcotic action of thiopental sodium (50 mg∙kg-1) is prolonged more than 2 times. When intravenous administration of hypertonic solutions to dehydrated (5.2 % of body weight) hyperosmolar coma develops, the duration of which correlates with the value of plasma osmolarity. Potentially life-threatening in rats is an increase in blood plasma sodium above 180 mmol∙l-1 or its osmolarity ˃360 mosm∙l-1. Osmotic volume index of urine is an effective non-invasive diagnostic criterion for disorders of water-salt metabolism and the effectiveness of its correction in experimental animals. Normally, in rats, this figure is (910.2±28.4), decreases sharply (more than 10 times) when stimulating diuresis with saluretics and may increase to (5061.3±54.2) with renal compensation of hyperosmolar syndrome

Keywords

• hyperosmolar hypohydration
• homeostasis
• osmotic volume index of urine