PubMed Health⌕ Search

Biomedical subjects

Iu V Natochin

Publications and source records attributed to Iu V Natochin.

At least 19 recordsLinked to original sources
PubMed2006

[Physico-chemical determinants of physiOlogical evolution: from protocell to the human].

One of the key physiological problems of evolution is elucidation of the role of environmental inorganic factors in origin of life. A statement is substantiated that a highly significant event in evolution of life was the appearance of protocells with the K cytoplasm in K water reservoirs with their subsequent adaptation to the environment in which Na dominated. This step was accompanied by replacement of the cell envelope with the cell plasma membrane. Precursors of animals' elaborated mechanism of maintenance of the K-cytoplasm with Na-counterkation in the environment. In plants, Na remains a trace element, in animals the Na and K contents are approximately equal, but they are present in different fluid phases. In animals presence of Na+ in the external medium, K+ inside cells has become an initial pre-requisition for electrogenesis and appearance of asymmetrical cells. Electrogenesis of these cells has become a physiological pre-requisition for cell differentiation, the appearance of the nerve cell. Asymmetrical cell has provided development of absorption, digestion, excretion, respiration. Formation of the inner medium has become a prerequisite for establishment of homeostasis. Serum osmolality, sodium concentration, pH, Ca2+ are the most rigidly maintained constants in the blood serum of humans.

Animals↗
PubMed2006

[Role of V1- and V2-receptors in mechanism of physiological paradox--an increase of reabsorption of the solute free water and simultaneous rise of diuresis].

In experiments on non-anesthetized rats with administration into stomach of water (5 ml/100 g body mass) direct correlation has been found between an increase of diuresis and excretion of solute free water (r = 0.98, p < 0.01), while after injection to these animals of 5 x 10(-11) M arginine-vasotocin - between an increase of diuresis and simultaneous rise reabsorption of solute free water (r = 0.8, p < 0.01). The rise of diuresis after the vasotocin injection is due to inhibition of sodium re- absorption, with the solute excretion fraction increasing from 2.6 +/- 0.2 % to 11.9 +/- 1.2, p < 0.001. A similar physiological paradox - an increase of diuresis with the simultaneous increase of reabsorption of solute free water - has been revealed at night hours in children with tendency for nocturnal enuresis (r = 0.64, p < 0.01). Mechanism responsible for this phenomenon consists in a rise of diuresis due to a decrease of sodium ion reabsorption in the ascending Henle loop limb. A problem is discussed of the homeostatic significance of a decrease of sodium reabsorption combined with an increase of solute-free water reabsorption; it is suggested that this phenomenon is based on a redistribution of reabsorption inside the nephron - a decrease of ion and water reabsorption in the initial parts of the nephron distal segment and an increase of solute free water reabsorption with the antidiuretic hormone-stimulated high osmotic permeability of terminal parts of renal tubules. An intraperitoneal injection of V1-anatagonist (OPC-21268) decreased the natriuretic component of response to arginine-vasotocin, while injection of V2-antagonist (OPC-31260) eliminated the antidiuretic component.

Absorption↗
PubMed2005

[Kidney accumulation of yellow fluorescent protein after its absorption in the rat intestine].

Yellow fluorescent protein (3.6 ng) was administered through a catheter into the Wistar rat intestine lumen. By the method of confocal microscopy it has been established that as soon as in 3 min this protein appears in the epithelial cells of ileum, is absorbed into the blood and accumulated in cells of the nephron proximal segment, not being revealed in the liver, though. The protein accumulation in kidneys continues for several hours. The yellow fluorescent protein is homogeneously distributed in enterocytes, while in epithelial cells of the proximal tubule this protein is localized in vesicles. The data obtained indicate absorption of non-degraded yellow fluorescent protein in the intestine and role of kidney in metabolism not only of endogenous, but also of exogenous proteins.

Absorption↗
PubMed2005

[Study of autacoids role in the regulation of circadian rhythm of the human renal function].

The circadian rhythm of urine formation was studied in younger (27 +/- 8 yr) and aged (76 +/- 3 yr) males. In 11 younger healthy examined persons a decrease of diuresis during the night as compared with the day time was due to a rise of solute free water reabsorption. In 31 aged males the change of the urine formation rhythm with increase of the nocturnal diuresis is based on a rise of osmolal clearance combined with an increase of the solute free water reabsorption. It is shown that blockade of autacoid secretion leads to normalization of the diuresis circadian rhythm. In 10 aged men, nocturia was due to a decrease of vasopressin secretion which resulted in a decrease of the solute free water reabsorption and an increase of diuresis. The obtained data are considered as an evidence for the role of renal autacoids, alongside with vasopressin, in regulation of the circadian rhythm of the kidney function.

Adult↗
PubMed2004

[Responses of the rat kidney to the water load test and vasopressin administered during normal feeding and fasting].

Parameters of water-salt balance in Wistar rats were compared on empty stomach and at standard alimentary regimen (satiated animals). On empty stomach, the blood serum osmolatity amounted to 284 +/- 2, while in satiated rats--to 290 +/- 5 mOsm/kg H2O (p < 0.05); sodium ion concentration on empty stomach lower, whereas no difference in potassium concentration was found. After an intragastric administration of water (5 ml/100 g body mass) to unanaesthetised rats, the blood serum osmolality decreased, while diuresis increased to an equal extent in both groups of rats. For 120 min after the water administration the rats on an empty stomach excreted 92.9% of the administrated fluid, whereas the satiated animals--80.7%. The urine composition differed qualitatively: in fasting rats the increment of diuresis was due to a rise of osmotic free water excretion, whereas in satiated rats--to an increase of excretion of osmotic active substances (including Na and K ions) with water and a simultaneous increase of the osmotic free water reabsorption in the kidney. After the water load and injection of 0.005 nmole/100 g body mass of arginine-vasopressin for 2 hr of the study, diuresis in both groups of animals decreased to an equal extent, but in fasting animals this was due mostly to an increase of the osmotic free water. The data obtained indicate that, under conditions of usual alimentary regimen, the response of kidney to the water load had a character of a volume-regulating response, whereas in fasting rats--of the specific osmorequlating one. A problem is discussed of the concept of norm under usual conditions and at certain clinically accepted restrictions, for instance, on empty stomach.

Animals↗
PubMed2004

[Immunocytochemical localization of vasopressin at its absorption by cells of rat small intestine].

Morpho-physiological characteristics of the transport of cyclic nonapeptide arginine vasopressin (AVP) across the rat intestinal epithelium was studied in experiments in vitro. A partial absorption of physiologically active AVP was followed when filling the isolated intestinal lumen by hormone solution. By methods of immunoelectron and immunofluorescence confocal microscopy, using polyclonal anti-AVP antibodies, cytoplasmic localization of AVP label was shown in enterocytes. The AVP label was also observed in the intercellular space in the basal area of epithelium. No label was revealed in the intercellular junctions, and no predominant label accumulation was found in any cytoplasmic structures of the epithelial cells. The obtained results are considered as evidence for the transcellular pathway of partial AVP absorption in rat small intestine.

Animals↗
PubMed2003

[Antidiuretic reaction of the human and rat kidney to peroral administration of arginine-vasopressin and desmopressin].

Water in amount of 5 ml/100 g body weight was administered through a gastric probe into the stomach in alert rats; subjects-volunteers drank 20 ml of water per 1 kg of body weight. This resulted in diuresis at the peak of which the excreted water fraction reached 23% in rats and 12.4% in human subjects, whereas excretion of the osmotically free water amounted to 0.103 +/- 0.018 ml/min/100 g body weight and 10.0 +/- 1.8 ml/min/1.73 m2 of the body surface, respectively. These data indicate a practically complete inhibition of the arginine vasopressin secretion. On intragastric administration of 10 micrograms of arginine vasopressin or 0.2 microgram of desmopressin, with water in rats, a prolonged and quite obvious antidiuretic response occurred, with a marked increase of reabsorption of the osmotically free water in kidneys. A direct correlation has been found between the dose of the intragastrically administered vasopressin in the dose range from 0.1 to 10 micrograms/100 g body weight and a decrease of clearance of the osmotically free water. In subjects volunteers, an antidiuretic reaction to administration of 0.2 mg of desmopressin with water, was found. The data obtained provide a direct proof of intestinal absorption of nanopeptides without loss of their physiological activity. Significance of the data obtained for physiology of digestion and for clinical medicine, is discussed.

Administration, Oral↗
PubMed2003

[The water-salt balance and renal function in space flights and in model experiments].

Study of a condition of mineral and water-electrolyte metabolism, function of kidneys, and their hormonal regulation during model experiments (hypokinesia, bed rest, immersion etc.), and also in space flights and in readaptation period, has shown a major role of water-electrolyte homeostasis during general adaptation of humans and animals to new conditions of life and to conditions of weightlessness in particular. The change in regulation of volumes of fluid milieu in an initial period of weightlessness was shown to be the consequence of redistribution of blood and hemodynamics of the shifts resulting in change of production of volume-regulation hormones, formation of negative water balance, and redistribution of fluid in the organism among various fluid compartments. At later stages of flight or long-term hypokinesia, a change of water-electrolyte homeostasis occurs with a decrease in the kidneys excretion of sodium, and diuresis, but with an increased excretion of calcium and production of ADH and RAAS hormones. Following returning to earth gravitation, the majority of astronauts have adaptive reactions, compensating for the loss extracellular fluid and mineral substances and formation of "earth" water-electrolyte homeostasis. For estimation of water-electrolyte homeostasis and the functions of kidneys in astronauts, various functional loading tests have been developed. The developed system of preventive maintenance is successfully used for abolition of adverse changes at various stages of space flight and in readaptation period.

Astronauts↗
PubMed2002

[Architecture of physiological functions: the same basis but new aspects].

The principles of physiological functions formulated by J. Barckroft (constancy of the internal medium, reserves, any adaptation as an integration, principle of antagonism, doubling of mechanisms) are compared with principles of modern physiology. The place and role of physiology in the life sciences are discussed. The necessity of taking into consideration 4 level of regulation of functions (the nervous system, hormones, autacoids, physicochemical factors of the extracellular fluid) is substantiated, as well as the necessity of identification of 4 levels of organization of physiological systems. The main role of the water-salt homeostasis in maintaining the cell volume is suggested. Significance of various types of receptors and second messengers in regulation and modulation of functions is shown.

Animals↗
PubMed2002

[Effect of vasotocin and prostaglandin E2 on absorption of water and ions in the large intestine of a grass fog].

In experiments on the frog Rana temporaria L. isolated colon, it has been shown that the rate of fluid absorption from the lumen is the highest when the lumen contains a hypotonic solution (22.5 mOsm/kg H2O), whereas the rate is lower in case of mucosal Ringer solution (225 mOsm/kg H2O). 10 nmole arginine-vasotocin rises the hypotonic fluid absorption, while 0.1 mumole prostaglandin E2 reduces the fluid absorption. Water content in the colon wall is the highest at mucosal hypotonic Ringer solution. 0.1 mumole prostaglandin E2 decreases hydration of the colon tissue. Secretion of prostaglandins E1 and E2 into the extracellular fluid of the colon has been established. The data obtained indicate participation of vasotocin and prostaglandin E2 in regulation of fluid absorption in the frog colon.

Animals↗
PubMed2002

[Physiological analysis of plasma hypo-osmolality in pneumonia].

AIM: To study the physiological mechanisms of plasma hypoosmolality in patients with pneumonia and on this basis to elaborate principles of therapy for this condition. MATERIALS AND METHODS: 52 individuals of different age, including 26 patients with pneumonia, were examined. Osmolality, the concentrations of ions of sodium, potassium, magnesium, and creatinine were measured in the serum. RESULTS: The patients with pneumonia were found to have osmolality, hyponatremia in combination with severe hypodiuresis, high urinary osmotic pressure and intensive reabsorption of osmotically free water in the kidney, which leads to blood dilution. As hypoosmolality usually causes higher diuresis and decreased urinary osmolality; hypodiuresis with high urinary osmolality in pneumonia is indicative of effective renal performance and its altered regulation evidently due to the hypersecretion of vasopressin or to the decreased formation of a number of autacoids in the kidney. CONCLUSION: Blood hypoosmolality and hyponatremia in the examined patients result from inadequate blood osmolality and high urinary osmotic concentrating. The principles of this condition in pneumonia are discussed and aquaretics are proposed for use as pathogenetic therapy.

Acute Disease↗
PubMed2001

[Electron microscopic study of colonic epithelial cells from the grass frog Rana temporaria under different intensity of water absorption].

Three cell types have been revealed in the epithelium of the frog large intestine: granular, mitochondria-rich, and mucosal cells. Under a low water permeability (0.12 +/- 0.10 mkl/(min.cm2)) the distribution of intramembrane particles (IMP) in the apical cell membrane was the same as in the most cell plasma membranes studied with freeze-fracture method. Under rising osmotic permeability and water absorption (0.43 +/- 0.05 mkl/(min.cm2)) the IMP distribution did not change. In these conditions, the quantity of fusion sites between granule membranes and the apical membrane increased, and the intercellular spaces in basolateral epithelial region were diluted. A a low water permeability, in addition to usual microtubules, bundles of noncentrosomal microtubules with associated osmiophilic globules were revealed. A comparative analysis has been made of the present evidence and previously obtained data on the frog urinary bladder epithelium.

Animals↗
PubMed2001

[Increase of water permeability and recovery of water impermeability of the frog urinary bladder].

The experiments carried out on the urinary bladder of the frog Rana temporaria L. have shown that the period of recovery of water impermeability after an increase of osmotic water permeability induced by arginine-vasotocin, desmopressin, or cAMP depends on the degree of increase of the osmotic permeability but not on the nature of the substance stimulating the increase of osmotic water permeability. The removal of the hormone in the absence of autacoids fails to recover the water impermeability. After cessation of the vasotocin action the water permeability decrease is delayed if phospholipase A2 and cyclooxygenase are inhibited by qiunacrine and voltaren, respectively. An agonist of V1-receptors has no effect on dynamics of the recovery of water impermeability. This recovery has been shown to depend on PGE2 concentration in the serosal solution after the hormone removal. The obtained results indicate that decrease of water permeability depends not only on removal of vasotocin or cAMP but also on involvement of autacoids.

Animals↗
PubMed2000

[Functional role of V1- and V2-receptors of the apical and basolateral membranes of the frog bladder epithelial cells].

Arginine vasotocin, 0.02--1 nM, increases osmotic water permeability of frog urinary bladder, arginine vasotocin after a simultaneous addition to the mucosal and serosal Ringer solutions rises the water permeability to a lesser degree than on the hormone addition only to the serosal solution. 1 nM remestyp, an agonist of V1-receptors, from the apical membrane decreases the hydroosmotic effect of arginine vasotocin added to the serosal Ringer solution. When added to the mucosal solution, combination of the same concentrations of arginine vasotocin and SR 49059, an antagonist of V--receptors, or desmopressin, agonist of V2-receptor alone, increases the effect of the same concentration of arginine vasotocin added to the serosal solution. 1 nM arginine vasotocin at the luminal membrane increases secretion into the Ringer solution of prostaglandin E, and prostaglandin E1 but not of prostaglandin F2 alpha. The data obtained indicate the presence of the arginine vasotocin receptors responsible for the hydroosmotic effect only in the basolateral membranes, while arginine prostaglandin E, participation is shown in modulation of the arginine vasotocin effect.

Alprostadil↗
PubMed2000

[Possible mechanisms of polyuria in progressive chronic renal failure].

AIM: Elucidation of the role of saluresis and osmotic diuresis in renal function of patients with chronic renal failure. MATERIAL AND METHODS: The trial included 68 subjects, among them 25 patients with chronic renal failure (CRF) of the third and fourth degree aged 16 to 72 years. Enzyme immunoassay was used to measure osmolality, sodium, potassium, magnesium, calcium and creatinine concentrations in the serum and urine as well as urine prostaglandin E2. RESULTS: Renal function was studied in CRF patients with a 75-90% fall of glomerular filtration rate. Creatinine clearance was 19.9 +/- 0.96, it varied in different patients from 10.6 to 29.7 ml/min. It is shown that diuresis does not correlate with the total ion excretion (Na+ plus K+)(r = 0.946, p < 0.0001). A correlation was found between excretion of these ions and Mg2+ ions this indicating location of reabsorption reduction in the thick ascending limb of Henle loop. In CRF patients (Na+ plus K+) excretion correlated with PGE2 excretion (r = 0.65, p < 0.0001). CONCLUSION: It is suggested that at this stage of chronic renal failure the mechanism of a diuresis increase is not due to osmotic diuresis but rather to secretion of prostaglandin E2 which inhibits cation reabsorption and stimulates diuresis. Differences are considered between osmotic diuresis and different types of saluresis; their possible mechanisms are discussed.

Adolescent↗