Uslovi lučenja renina

1) Gradual deprivation of oxygen with consequent cooling by Gjaja's method lowers blood pressure (BP) of rats for more than 50 per cent, and oxygen consumption in their tissues even more. 2) These two factors bring about the secretion of renin in the kidney and they make it possible to follow the conditions of its secretion: the moment of its discharge, the duration of its circulation and the eventual stimulatory or inhibitory effects of drugs on the secretion. 3) The experiments showed that the secretion of renin begins immediately during the cooling and that BP rises during the first few, weeks of cooling. After 14 days cooling BP is markedly enhanced. If the animal is· cooled 14 days more, BP decreases because of myocardial damage. 4) The adrenalectomized rats exhibit the same changes as the intact ones. 5) The examination of fundus oculi shows a constriction of retinal blood vessels similar to that of renal hypertension; these spasms of retinal vessels appear already during the stage of cooling. 6). Atropine, Pendiomide, Papverine and Euphiline prevent the discharge of renin in cooled rats, for the fundus oculi shows dunng cooling the same changes with these drugs as without them. 7) Gynergen and hydergin condition the same changes in fundus oculi both of cooled and non­cooled rats, which leads to the conclusion that they stimulate the secretion of renin; they probably lower BP, by a paralysis of the sympathetic, in the kidney so much that renin is secreted. Ergometrine does not stimulate the secretion of renin. 8) The question had arises whether the pressoceptive mechanisms might not be at the same time chemoceptive. After renin was found in crush syndrome, shock glomerulonephritis and in eclampsia, it was supposed that it could be so. S. c. injections of histamine caused in rats also a spasm of retinal vessels, which justifies the assumption that presso-­ and chemoreceptors play a role in the secretion of renin by the kidney.