Maintaining the tone of the extracellular fluid in a very narrow range is extremely important for the full function of the cells of the body. Extracellular osmolarity regulates both the shape of the cell and the intracellular concentration of various ions. In turn, adequate concentrations of ions in extracellular media are necessary for the proper function of ion channels, the action of potentials and other models of intercellular interaction.
A complex regulatory system, including endocrine, nervous and paracrine mechanisms, is responsible for maintaining the water-salt balance and stability of plasma osmolarity in the body. The components of this system are the axis of the hypothalamus – neurogopathy, osmoreceptor and baroreceptor regulation systems and the kidney. The mechanisms of osmotic sensors and effectors control the regulation of vasopressin release and signal transduction, while volumetric homeostasis is mediated mainly through the action of the renin-angiotensin-aldosterone system.
Vasopressin
The priority of the hypothalamus-neuro-pituitary axis in the regulation of water-salt metabolism is primarily due to the fact that the synthesis, storage and secretion of the antidiuretic hormone vasopressin is carried out by this very system.
Vasopressin is a nonapeptide consisting of a six-membered ring closed by a disulfide bridge, and a three-membered terminal part. He first isolated vasopressin and deciphered its structure V.de Vigneaud in 1953-54. Subsequently, arginine-vasopressin was synthesized (1956). Vasopressin is synthesized in the supraoptic and paraventricular nuclei of the hypothalamus. The synthesized hormone forms complexes with neurophysins, carrier proteins, and is transported along axons through the supraopticohypophysial tract to the neurohypophysis, where it is released under the action of various stimuli.