[A microdissection study of the kidney in the great gerbil Rhombomys opimus in early postnatal ontogeny]. / Mikrodissektsionnoe issledovanie pochki bol'shoi peschanki Rhombomys opimus v rannem postnatal'nom ontogeneze.

It has been demonstrated that in gerbils, similar to other mammals, superficial nephrons are formed in postnatal ontogenesis in the last turn. However, the development of these nephrons and thin parts of Henle's loops in intracortical and juxtamedullary nephrons takes place earlier than in other mammals, which may be caused by specialization of gerbils to arid conditions.

[Possibilities of deposition of electrolytes in the skin in different states of water-salt metabolism]. / Vozmozhnosti deponirovaniia élektrolitov v kozhe pri razlichnykh sostoianiiakh vodno-solevogo obmena.

Isotonic solutions of NaCl, KCl or MgCl2 (5 ml/100 g body weight) were introduced into the stomach of rodents. Participation of the skin in the water--salt homeostasis involved a temporal unspecific detaining of ions which were subsequently excreted from the organism. The NaCl and KCl loads increased the amount of exchangeable sodium in the skin structures. A similar response to all the salt loads was observed in abdominal and spinal parts of the skin.

Volume and ion regulating renal functions in the big gerbil (Rhombomys opimus L.) and the water vole (Arvicola terrestris L.).

1. After iso-osmotic salt loading (1% NaCl, 1.25% KCl, 0.75% MgCl2 solutions, each load making up 5% body weight) the water voles excreted 66.2% sodium, 84.4% potassium, 18.8% magnesium over a 4 hr period. The big gerbil excreted 20%, 58.9% and 7.1% respectively over the same period. The volume of the water excreted was greater in the case of the water vole. 2. There were no considerable changes in plasma ion concentration in rodents of the species studied after salt loading. 3. The gerbils and water voles had no significant changes in the renal cortex electrolyte concentrations as a result of isotonic salt loads. The highest sodium cortico-papillar gradient was found in the gerbils when experimenting with the isotonic NaCl loading. It was somewhat lower with the KCl load, and significantly lower with water and MgCl2 loads. 4. Under the same experimental conditions, no major changes in the papilla sodium concentration were found in the water voles. 5. The concentrations of potassium, calcium and magnesium were practically alike in all zones of the renal tissue of both rodent species, ion loads producing no effect. 6. The comparison of the renal volume and ion regulating function in rodents with different urine osmotic concentration systems proves the independent existence of renal functions. The greater rate of renal fluid and ion excretion in the water voles is coupled with less specific ion regulation.

[Micropuncture study of sodium chloride and bicarbonate reabsorption in the proximal tubule of the lamprey, Lampetra fluviatilis, kidney]. / Mikropunktsionnoe izuchenie reabsorbtsii khlorida i bikarbonate natriia v proksimal'nom kanal'tse pochki minogi Lampetra fluviatilic.

Proximal tubules of the kidney have been injected in vivo with isotonic solutions (in mequiv./1: 120 NaCl; 120.4 Na, 114.0 Cl, 6.4 HCO3 and 120 Na, 60 Cl, 60 HCO3) and half time (t 1/2) of fluid absorption was measured by shrinking drops technique. The value of t 1/2 was found to be significantly lower for NaCl solution than for NaCl--NaHCO3 (1:1) one. These data suggest that proximal reabsorption of chloride and bicarbonate is provided by separate specific transport systems.