Abstract
Purpose. To study urea kinetics in the body after liver resection in the experiment. Material and Methods. Experiments were carried out on 45 white female rats weighing between 180 g and 220 g. Liver resection (LR) was performed under ester anesthesia, wherein 15—20% of the organ weight was removed. Urea content was studied in biological fluids (arterial blood, venous — v.porta, v.hepatica, v.renalis — blood, choledochal bile, urine), and tissues of visceral organs (the thyroid gland, lungs, heart, liver, kidneys, spleen, stomach, intestine) on days 3, 7, and 14 after LR. Results. LR, while reducing the urea content in the v. hepatica blood, does not lead to similar changes in the arterial blood. This is accompanied by increased urea reabsorption in kidneys and higher v.porta blood urea content, which, depending on the postoperative time, results either from reduced urea excretion into the small intestine lumen or from its greater production by enterocytes followed by metabolite intake into the portal blood flow. The urea intake from hepatocytes into the hepatic bile ducts did not change on day 3 after LR; however, it increased on day 7 and slowed down on day 14. LR caused no changes in the gastric tissues urea content; never theless, it led to its increased content in the duodenal and colonic tissues. Without affecting the cardiac muscleurea content, LR entailed its increase in the lungs and thyroid gland on postoperative days 3, 7, and 14. At the background of absence of similar changes in the arterial blood data indicates promotion of urea production by the cells of these organs or metabolite retention therein. Conclusions. LR not only changes urea kinetics in the portal system organs, but also activates extrahepatic mechanisms aimed at preventing development of the arterial blood urea deficit because of its abnormal intake from the resected organ into the central blood flow.
Highlights
Одним из конечных продуктов белкового обмена у млекопитающих является аммиак
As can be seen from table 1, the normal content of urea in the v.hepatica blood significantly exceeds the same indicator in the arterial blood and v.porta blood, respectively, by 25% and 58%
Unlike v.hepatica blood, the concentration of urea in the common duct bile did not differ significantly from the similar index in v. porta blood, but com pared to arterial and v. hepatica blood it was reduced, respectively, by 19% and 35%
Summary
Одним из конечных продуктов белкового обмена у млекопитающих является аммиак. Уве личение его концентрации оказывает токсическое действие как на клетки [1, 2], так и организм в це лом [3, 4]. Одним из основных путей нейтрализа ции аммиака является его необратимое связыва ние через синтез мочевины [5], который происходит в гепатоцитах перипортальной зоны дольки печени [6], где обнаружен полный набор ферментов орнитинового цикла Кребса Хенсе ляйта [1], включая аргиназу. Поскольку аргиназа обнаружена не только в печени, но и других органах и тканях млекопитающих [7], то можно говорить о «внепе ченочном» образовании мочевины, при котором не происходит нейтрализации аммиака. Между тем различная активность аргиназы в тканях [7], позволяет ожидать неодинаковый вклад каждого органа в формирование физиологической кон центрации мочевины в крови. Целью настоящего исследования явилось изучение ки нетики мочевины в организме после резекции пе чени в эксперименте
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