Biomedical subjects

V M Gontmakher

Publications and source records attributed to V M Gontmakher.

At least 19 recordsLinked to original sources

PubMed1992

[Functional morphology of parathyroid cells in disorders of calcium metabolism].

Cell composition of the parathyroid gland was studied under normal conditions, after the hypo- or hyperloading with calcium gluconate and at hyperfunction. Three types of parathyrocytes were established that probably reflect different stages of their life cycle: the first--poorly differentiated cell, the second--mature differentiated cell and the third--degenerated cell. The majority of cells were represented by the parathyrocytes of the 2nd type the varieties of which reflect a non-active (A-subtype) and active (B-subtype) phases of secretion. The number of A-cells is increased under the condition of the hyposecretion and the relative number of B-cells under the condition of experimental hypersecretion.

Animals↗

PubMed1989

[Cellular mechanisms of compensatory processes of the kidney in relation to the mass resected].

As a result of comparative investigation of compensatory processes in the kidneys at various degree of their resection, the most general regularities in these processes have been revealed: an initial functional strain of renal cells and their ultrastructures, the secondary increase in hypertrophy and hyperplasia of the renal cells and their organelles. The degree of manifestation of these regular reactions directly depends on the mass of the resected part of the kidney. Subtotal resection of the kidney (80%) is an operation that gets out of the limits of the organ's compensatory possibilities. A sharp decrease, up to complete disappearance of its cellular division in 2-3 weeks after the operation is of great importance. Mechanism for development of renal insufficiency is evidently connected with absence of cellular renewal against the background of their hyperfunction and their quick worn out, that is, evidently, resulted in deficiency of renal epithelium and functional defectiveness connected with it in the remained renal mass.

Adaptation, Physiological↗

PubMed1988

[The role of the ultrastructure of the intercalated cells of the kidney collecting tubules in rats in secreting hydrogen ions].

Upon experimental metabolic acidosis in rats, induced by a long-term per os administration of a 10% ammonium chloride solution, elevation of titred acidity and ammonium level in rat's urea was registered, in addition to an increased number of intercalated cells in collecting tubules of kidney medullar zone, where the highest carboanhydrase activity occurred. The structural and functional unit of the intercalated cell is a smooth vesicle having presumable H+-,K+-translocating exchange pump within its membrane. The vesicles accumulating gradually H-ions move to the apical cell membrane to release their content by exocytosis into the tubule space. Under H+-ion hypersecretion, upon experimental acidosis, the vesicle membrane is built into the apical plasma membrane, where H+,K+-exchange occurs, thus intensity of this process increasing. The apical plasma membrane of the cell extends its surface at the expense of intracellular canaliculi that are formed.

Acid-Base Equilibrium↗

PubMed1987

[Functional morphology of interstitial cells of the renal medulla after treatment with indomethacin and unilateral nephrectomy].

The ultrastructure of the renal medullary interstitial cells was compared with the quantitative estimation of the interstitial space and its proteoglycan content after stimulation (left nephrectomy) and inhibition (indomethacin administration) of the prostaglandin synthesis. Lysosomes were found to play a functional role in the lipid granule depletion and arachidonic acid release. The ratio of lysosomes to lipid granules within the interstitial cells may serve as a criterion of their functional activity in the process of prostaglandin synthesis. Functional state of the rough endoplasmic reticulum of the interstitial cells was indicative of the cells involvement in the production of the mediate intercellular substance.

Animals↗

PubMed1986

[Various structural aspects of the functional transformation of the kidneys during adaptation to fasting].

Electron microscopic and morphometric investigations of the rat kidneys in 3-6 days after a complete fasting have revealed certain ultrastructural signs of an increased proteolysis in the proximal parts of the nephron canaliculi and structural manifestation in the glomerular blood stream changes, that represents an important condition for passing proteins the glomerular membrane. In this connection, it is supposed that at adaptation to fasting the kidney ensures proteolysis of endogenic-proteins--the first stage of their reconstruction. This function is ensured by structural-functional reconstruction of the juxtaglomerular complex, vessels of the filtrative apparatus and by the proteolytic system in the proximal part of the nephron canaliculus.

Adaptation, Physiological↗

PubMed1977

[Structural aspects of the decrease in several renal functions in old rats].

The proliferation, size and ultrastructure of the renal cells was studied in 32-38-month-old rats. At this age no dividing epithelial cells were found and their size was enlarged (in proximal areas of the nephrons by 30,2%, in the collecting tubes by 22%). The decreased rate of glomerular filtration in aged rats in dependent on the disturbance of hemodynamics in the glomerular capillaries, for which, to certain extent, the hypofunction of the rhenin-secreting complex is responsible. The reduction of microvilli, hypoplasia of the basal folds, changes in the orientation and size of the mitochondria are considered to be the structural basis of the decreased reabsorbtion in the proximal part of the nephron. In the distal part of the nephron the organization of the plasmalemmal-mitochondrial sodium pump is disturbed. In the collecting tube the number of dark cells becomes less, they shrink and disintegrate, which is considered to be responsible for disorders in the function of the hydrogen ions secretion. The decreased level of the physiological regeneration of cells is likely to underlie the disorders in renal functions in aged rats. The lack of proliferation gradually results in a deficiency of epithelial cells, their hypertrophy, functional stress and wear.

Aging↗

PubMed1976

[Cells secreting hydrogen ions into the renal tubules].

The ultrastructure of the epithelial cells of the renal tubules and of parietal cells of the stomach in intact rats was compared with that in animals with acute metabolic acidosis and animals kept on dry food. The studies were conducted on white male rats weighing 120-150 g. Acute metabolic acidosis was induced by a single intraperitoneal injection of 1 ml of a 1% solution of ammonium chloride. Pieces of the tissue for electron microscopy were fixed with OsO4 and poured with araldit and epon-812. The studies conducted revealed the ultrastructural similarity between the dark cells of the distal gyrous tubule and collecting tubes with parietal cells of the stomach. This similarity was seen from the one-type distribution of mitochondria of the smooth-walled vesicules and appearance in acidosis of intracellular and intercellular tubules. Such cells were not revealed in the proximal tubules, however, consideration of the results obtained and the literature data makes it possible to suggest that all cells of the proximal part of the nephron secret H+-ions, this being one of their functions. In the distal gyrous tubules and in the collecting tube this function is realized by specialized dark cells.

Acidosis↗

PubMed1976

[Ultrastructural-cytochemical features of the plasma membrane of sodium-transporting cells].

Electron microscopic and biochemical studies of the ATP-ase activity in different regions of the nephron and in the kidney microsomal fraction of the rat have revealed a pronounced increase of the total and Na+-+K+-ATP-ase activity in the process of compensatory hypertrophy. A decrease of the enzymatic activity was noted predominantly in proximal tubules under loading the animals by isotonic NaCl solution and after adrenalectomy--mainly in distal tubules. This speaks of the inhibition of the sodium-reabsorbing system in them. The transport of isotonic fluid in collecting tubes is accompanied by widening intercellular lacunae together with an increase of the ATP-ase activity of the lateral plasmic membrane of neighbouring cells. The data obtained suggest a close correlation between the electron-microscopically revealed ATP-ase activity of the plasmic membrane of tubular cells and the functional activity of the sodium-transporting system. A morphological equivalent of the sodium pump is a plasmolemma--mitochondrial pump which is characterized by: a) well developed foldness of the basal plasmic membrane where the enzymatic system is disposed; b) the high total and Na++K+-ATP-ase activity cytochemically and biochemically revealed; c) numerous regularly disposed mitochondria, having close contacts with the folds of the basal plasmic membrane.

Adenosine Triphosphatases↗

PubMed1975

[Compensatory renal hypertrophy after nephrectomy in newborn rats].

The process of the kidney compensatory hypertrophy in young rats has been studied after nephrectomy on the 2nd day of life. The intact kidney was investigated by morphometrical and electron microscopical methods from the 1st day till the 3rd month after operation. The kidney compensatory hypertrophy in the early postnatal ontogenesis is accompanied by the acceleration of growth and differentiation of renal structures. The hypertrophy involves three successive steps: (1) functional tension of ultrastructures; (2) expressed hyperplasia and hypertrophy of cells; (3) structural-functional specialization. Among the cellular factors of the kidney compensatory growth at this age, the main role is played by the process of cell hyperplasia.

Animals↗

PubMed1975

[The relationship of mesangial cells to the renal juxtaglomerular apparatus].

A comparison between the ultrastructural characteristics of mesangial cells and myoepithelioid ones of the juxtaglomerular apparatus (JGA) of the kidney was carried out under conditions of activation and reduction in the secretion of renin. Bilateral adrenalectomy and parenteral protein loading were used for intensifying the activity of JGA. The state of a decreased functional activity of the JGA was studied under conditions of 7-day starvation. It was established that both in the case of adrenalectomy and in protein loading mesangial and myoepitheloid cells showed a similar type of reaction, the essence of the latter being activation of the protein synthesis. Moreover, in mesangial cells there were observed secretory granules similar structurally to those of the myoepithelioid cells. A-Decrease in secretion in myoepithelioid cells of the JGA in starvation was accompanied at the same time by a reduction in the synthetic activity of mesangial cells. An analogous reaction of mesangial and myoepithelioid cells in activation and reduction of renin secretion justifies the suggestion about the functional unity of these cells in producing biologically active substances of the JGA of the kidney.

Adrenalectomy↗

PubMed1974