The Acute Effect of Vasopressin Upon the Composition of the Rat Renal Cortex and Medulla

Abstract

Rats in water diuresis were given intravenous injections of vasopressin, or of isotonic NaCl for controls. Serial urine sampling showed that maximal osmolality and minimal flow were achieved half an hour after vasopressin injection, and that urea excretion was low at this time. In animals killed half an hour after injection, the composition of the renal papilla, medulla and cortex was studied.The urea and ammonium concentration and content increased in the inner medulla after vasopressin injection, and the water content increased in all the kidney slices, but significantly so only in the papilla. The medullary osmolality did not alter appreciably, the accumulation of urea and ammonium being counterbalanced by the increase of water. The urine osmolality did not reach the level found in the medulla. No appreciable change of sodium or potassium concentration or content of kidney slices was observed after vasopressin injection. The results are discussed in relation to means whereby vasopressin induces antidiuresis and urinary hypertonicity.IN the preceding paper [Saikia, 1965], the differences between the composition of the renal medulla in hydropenic and water diuretic rats were studied. It is commonly supposed that these differences are due to the presence or absence of vasopressin. The present paper attempts to discover how far this is true, that is, how far the condition in water diuresis can be altered rapidly to that of hydropenia by an injection of vasopressin.Some workers studying this problem have used very large doses of vasopressin [Jaenike, 1961;Levitin et al., 1962], though Perlmutt [1962] has used a dose nearer the likely physiological range, as has been here attempted. METHODSWater diuresis was produced in hydrated rats by the methods described in the previous paper [Saikia, 1965].Two and a half hours after water injection, when the diuresis was maximal and steady, thirteen rats were given Lysine-vasopressin (Sandoz; 04 mu per 100 g. body weight in isotonic saline) by single intravenous injection into the tail vein, and thirteen had only isotonic saline to serve as control.Urine was collected at the time of injection, and in ten rats of each group half an hour later, immediately before removal of kidneys. Residual urine in the bladder was measured.In three rats of each group, micturition was induced, by brief ether inhalation, at 15 min. intervals after injection for 1 hr. The kidneys were not removed in these

Sequestration of urea and nonurea solutes in renal tissues of rats with hereditary hypothalamic diabetes insipidus: effect of vasopressin and dehydration on the countercurrent mechanism.

“…In contrast, Jaenike has pre-sented indirect evidence suggesting that vasopressin does not enhance the medullary sequestration of nonurea solute (3). Although other investigators have reported similar studies (4,5), there still is no agreement whether or not vasopressin promotes the medullary sequestration of sodium. The availability of rats with a genetic, apparently absolute, defect for synthesizing vasopressin (6) seemed to present an ideal opportunity for reinvestigating this problem.…”

Composition of the Renal Cortex and Medulla of Rats During Water Diuresis and Antidiuresis

“…Ten rats and three hamsters were studied during water diuresis induced by intraperitoneal distilled water (4 ml./100 g. body weight, injected under light ether anaesthesia). G. A. Bray [personal communication] found this to produce a more prolonged water diuresis than did intragastric water, and his findings have been confirmed [Saikia, 1965]. The hamsters and five of the rats had access to tap water and cabbage leaves, and the other five rats were deprived of food and water for 24 hr.…”

“…Whatever the mechanisms whereby sodium accumulation is maintained in the medulla, they still operate during water diuresis, whereas the urea accumulation is largely dispersed. How far vasopressin can reverse these changes will be considered in the subsequent paper [Saikia, 1965].…”

Dehydration modifies guanidino compound concentrations in the different zones of the rat kidney

“…Each of the natural GCs: Arg, GAA, guanidinosuccinic acid (GSA), CT, creatinine (CTN), homoarginine (HArg), α-N-acetylarginine (α-N-AA), β-guanidinopropionic acid (β-GPA), γ-guanidinobutyric acid (γ-GBA), α-keto-δ-guanidinovaleric acid (α-keto-δ-GVA), guanidine (G) and methylguanidine (MG) exhibit typical distribution patterns along the cortico-papillary axis [16]. Moreover, it is noteworthy that, in adult rats, the tissue concentrations of α-keto-δ-GVA, GSA, CTN, MG, α-N-AA and γ-GBA increase steeply from the inner stripe of the outer medulla to the papillary tip and, thus, constitute gradients which run in parallel to the well-known urea and osmotic gradients [26,31]. These latter two gradients are known to change in response to antidiuresis and diuresis and changes in medullary osmolality are accompanied by corresponding variations in the intracellular concentrations of organic osmolytes.…”