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Biomedical subjects

A L Markel'

Publications and source records attributed to A L Markel'.

At least 19 recordsLinked to original sources
PubMed2007

Effects of rapid and slow cooling on thermoregulatory reactions in hypertensive rats after administration of calcium.

Iontophoretic administration of calcium ions into the skin close to the application site of a cold stimulus decreased the threshold of thermoregulatory reactions in hypertensive rats to a greater extent than in normotensive control animals, which may be evidence that the tissues involved in thermoregulatory reactions to cold have a greater sensitivity to calcium in hypertensive rats. The initially earlier onset of vascular and metabolic reactions and the increase in the vascular reaction seen in hypertensive rats became more marked after administration of calcium. Treatment with calcium, increasing the vascular reaction to cooling, facilitates a more marked discrimination between hyper-and normotensive animals in terms of the appearance of the vasoconstrictor reactions of skin blood vessels in response to cold. The effects of the added calcium on cold-dependent reactions depended on the rate of cooling.

Animals↗
PubMed2006

[Comparative analysis of conditioned passive avoidance retention in rats with different forms of inherited arterial hypertension].

Comparing behavioral traits of anxiety in elevated plus-maze and retention of passive avoidance response in two rat strains with hereditary arterial hypertension ISIAH (inherited stress induced arterial hypertension) and SHR (spontaneously hypertensive rats) has shown the following. The SHR rats demonstrate impairment in retrieval of passive avoidance, hyperactivity and low anxiety. ISIAH rats showned better avoidance performance, average level of anxiety and activity. The interdependence of two pathologies: hypertension and memory impairment is discussed.

Animals↗
PubMed2005

[Effect of rapid and slow cooling on thermoregulatory responses in hypertensive and normotensive rats after calcium administration].

The effect of iontophoretic administration of calcium ions to skin in the area of cold stimulus application on the thermal thresholds and the magnitude of cold defense responses in normotensive Wistar and hypertensive ISIAH rats was studied. In thermoneutral conditions, administration of calciumions wos without effect on the measured thermoregulatory parameters. Under the effect of calcium, the thresholds of all the thermoregulatory responses to cooling (such as heat loss, oxygen consumption, shivering) are lowered and the values of heat loss and shivering thermogenesis are considerably increased. The effects of calcium on thermoregulatory responses depend on the rate of cooling. All changes are more expressive in hypertensive rats. The increased sensitivity of hypertensives to calcium suggests that change in their calcium metabolism may be a cause of the observed shifts in the thermoregulatory response to cold.

Animals↗
PubMed2005

[Stereomorphometric study of target organs in rats with hereditary stress-induced arterial hypertension at different periods of postnatal ontogenesis under changed conditions of nursing].

In rats with inherited stress-induced arterial hypertension (ISIAH strain), myocardium, adrenal gland, and renal glomerular apparatus were studied at different periods of postnatal ontogenesis (3 weeks and 6 months) to assess the influence of the changed conditions of nursing on the development of a hypertensive status and structural-functional characteristics of target organs. It was demonstrated that nursing of rats by foster normotensive Wistar females exerted a modulating influence upon the realization of stress-determined program of arterial hypertension development, seemingly delaying it and alleviating the negative consequences in respect to the target organs, through increased effectiveness of recruitment of adaptive-compensatory organism reserves, however, on the whole, it did not interrupt this program.

Adrenal Glands↗
PubMed2004

Structural characteristics of cardiomyocytes in the right atrium of NISAG rats.

Electron microscopy and stereomorphometric analysis of hypertrophic cardiomyocytes in the right atrium of NISAG rats revealed signs of activation of biosynthetic processes: increased relative volume of euchromatin (compared to Wistar rats), high density of nuclear pores, presence of large numerous Golgi complexes, and well-developed endoplasmic reticulum. The numerical density of secretory granules in the cytoplasm of cardiomyocytes in NISAG rats significantly surpassed that in Wistar rats. However, these granules in NISAG rats were smaller than in Wistar rats. The presence of numerous secretory granules and increased ratio of forming and dissolving structures suggest that this pool is characterized by high turnover rate, i.e., intensive synthesis and rapid elimination (consumption) of natriuretic peptide. Hypertrophy and hyperactivity of endocrine function in atrial cardiomyocytes of NISAG rats can be considered as a compensatory reaction to hypertension.

Animals↗
PubMed2003

Hypotensive activity of ultralow doses of antibodies to factors involved in the regulation of vascular tone.

Hypotensive activity of ultralow doses of antibodies to some endogenous substances involved in the regulation of vascular tone was studied on NISAG rats with hereditary stress-induced arterial hypertension. It was found that antibodies to angiotensin II and its receptor in ultralow doses markedly reduced systolic blood pressure, which was reproducible after repeated treatment. The course of peroral treatment with antibodies to endothelin and endothelial NO synthase in ultralow doses did not decrease systolic blood pressure.

Angiotensin II↗
PubMed2003

Effect of chronic stress during early postnatal ontogeny on structural characteristics of the myocardium and glomerular apparatus of the kidneys in NISAG rats.

We studied structural characteristics of the myocardium and glomerular apparatus of the kidneys in 3-week- and 6-month-old male NISAG rats (hereditary stress-induced arterial hypertension) subjected to handling on days 1-21 of postnatal ontogeny. The animals were daily isolated from mothers for 10 min. Handling did not modulate the development of arterial hypertension and typical morphological signs in the myocardium and kidneys.

Animals↗
PubMed2003

[A search for genetic loci responsible for emotional stress-induced arterial hypertension in the ISIAH rats].

Hypertension is a widespread human disease caused by a complex interaction of a series of the genetic factors with both each other and the environmental conditions. In this study we aimed at determining the candidate genetic loci responsible for hypertension in the ISIAH rats and studying the dynamics of the relevant genetic and physiological mechanisms in rat ontogeny. The candidate genetic loci were identified from association of the microsatellite markers linked to these loci with arterial hypertension in rat F2 hybrids exposed to stress. Two populations of F2 hybrids of different age (3-4 and 6 months) were obtained by crossing hypertensive ISIAH and normotensive WAG rats. We present the results of cosegregation analysis for the following loci: the gene for the Na+, K(+)-ATPase alpha 1 subunit isoform (Atp1a1), the endothelin-2 gene (Edn2), the low affinity nerve growth factor receptor gene (Lngfr), and a region of chromosome 10 marked with the D10Rat58 microsatellile located 3 cM away of the aldolase C gene (AldC). The results obtained allowed us to localize the genes responsible for the stress-induced arterial hypertension in the ISIAH rats to the Atp1a1 locus (P < 0.05), chromosome 2 and to the Lngfr gene locus (P < 0.05), chromosome 10. The association of hypertensive status with the Lngfr gene was found only in young ISIAH rats whereas in adult rats of this line, hypertension was associated with the Atp1a1 locus.

Age Factors↗
PubMed2003

[Characteristics of glucocorticoid receptor gene expression in spontaneously hypertensive rat strain].

In ISIAH rat strain with stress-sensitive form of hypertension, the expression level of glucocorticoid receptor (GR) gene has been evaluated in hippocampus, hypothalamus and pituitary under basal and 2-hr restraint stress conditions. Corticosterone (CS) level in peripheral blood was also evaluated. Normotensive WAG strain was used as a control. Under basal condition, there were no interstrain differences in GR-mRNA level in any brain region under study. However, under stress condition, ISIAH rats demonstrated a significant fall of GR-mRNA in hippocampus and increase the pituitary gland as compared to basal level. On the contrary, no differences with basal level were found in stressed WAG rats. CS concentration in blood was nearly the same in nonstressed WAG and ISIAH rats. Stress influence led to a marked increase of CS in both strains. However CS level was significantly higher in stressed ISIAH rats than in stressed WAG group.

Animals↗
PubMed2002

[Effect of chronic stress during prepubertal period of life on development of inherited arterial hypertension].

The immediate and long-lasting effects of environmental stress during prepubertal life on arterial blood pressure (AP) were studied in rats with inherited stress-induced arterial hypertension (ISIAH) and normotensive Wistar rats. Two models of chronic stress (the 21st-32nd postnatal days) were used: repeated handling and unpredictable stress of daily exposures to a variety of mild physical or psychoemotional stressors. Chronic prepubertal stress did not affect the basal or stress-induced AP levels in young or adult Wistar rats. In ISIAH rats, chronic stress during the early phase of hypertension development did not accelerate its formation and did not augment its manifestation in adults. Moreover, the basal AP was decreased in young and adult ISIAH rats exposed to prepubertal stress as compared to the age-matched controls. AP elevation under acute stress conditions was lower in young ISIAH rats exposed to unpredictable stress. No long-lasting effect of prepubertal stress on acute stress-induced AP elevation in adults was found. The conclusion was drawn that moderate physical and psychoemotional training at prehypertensive stage can positively affect the development of inherited arterial hypertension.

Aging↗
PubMed2002

[Structure of the adrenal gland in rat strain with hereditary stress-induced arterial hypertension nursed by Wistar dams].

The comparative investigation of the adrenal structure in two groups of rats of Inherited Stress-Induced Arterial Hypertension (ISIAH) strain was conducted. The animals of the first group were nursed by normotensive Wistar rats, while those of the second (control) group were reared by their own mothers. The volume of the adrenal medulla in rats of the first group was found to exceed that in the second group. In the adrenal zona glomerulosa and zona fasciculata of 3-week-old rats of the first group parenchymal-stromal ratio and the average volume of adrenocorticocytes were lower than those in the animals of the second group. This was accompanied by a decrease in mitochondrial volume density and accumulation of lipid droplets in the cytoplasm, indicating a reduction of hormone-producing activity of endocrinocytes in the animals the first group as compared to controls. By 6 month of age, arterial pressure and quantitative parameters of adrenal medulla and cortex in the animals the first group were..... as compared to those in the second group. It is suggested that the nursing of ISIAH rat pups by normotensive Wistar dams had modulating effect on the adrenal structure and therefore on arterial hypertension development.

Adrenal Cortex↗
PubMed2002

[Function of hypothalamic-pituitary-adrenocortical system in hypertensive rats of ISIAH strain].

Functional activity of hypothalamic-pituitary-adrenocortical axis has been studied under control and restraint stress conditions in rats with inherited stress-sensitive arterial hypertension (ISIAH strain) and in normotensive WAG (Wistar Albino Glaxo) strain. The levels of hypothalamic CRH-mRNA (in control and 2 hrs stress), pituitary and plasma ACTH and plasma corticosterone (in control and after 5, 15 or 30 min of restraint stress), were evaluated. Hypothalamic CRH-mRNA level was found to be approximately the same in the control rats of both strains. In control conditions, the pituitary and plasma ACTH content in ISIAH rats was significantly lower whereas the corticosterone level in the plasma differed from each other in both strain. The restraint stress resulted in a statistically significant increase of the CRH-mRNA in ISIAH rats and not in the WAG rats. Moreover, in spite of the lower ACTH level in stressed ISIAH rats, the corticosterone blood plasma concentration in hypetensive rats was significantly higher. The data obtained confirm the idea that the stress-dependent hypertension might be related to an enhanced sensitivity of the main endocrine links involved in the stress response organization.

Adrenocorticotropic Hormone↗
PubMed2001

Structure of renal glomeruli in hypertensive NISAG rats reared by normotensive females.

Morphometry of ultrastructural components of renal glomeruli in 3-week- and 6-month-old rats with hereditary stress-induced arterial hypertension (NISAG rats) reared by normotensive Wistar females showed deceleration of the development of arterial hypertension in NISAG rats and attenuated its negative consequences for kidneys as the target organs.

Animals↗
PubMed2001

Selenium content and blood antioxidant activity in rats with hereditary arterial hypertension during experimental myocardial infarction.

The dynamics of selenium content in the plasma, lymph, and myocardium and plasma antioxidant activity were studied in male NISAG (hereditary stress-induced arterial hypertension) and Wistar rats with acute myocardial infarction and during recovery. In NISAG rats the decrease in selenium content correlated with the decrease in antioxidant activity. This probably aggravates the symptoms of experimental myocardial infarction in animals with hereditary arterial hypertension.

Animals↗
PubMed2001

Development of hypertensive status in NISAG rats reared by normotensive Wistar rats.

Parameters of the cardiovascular system and the content of corticosterone, thyrotrophin, thyroxin, and triiodothyronine in the plasma, and norepinephrine in the myocardium were determined in male NISAG rats (hereditary stress-induced arterial hypertension) reared by normotensive Wistar rats. Cross-rearing of hypertensive rat pups by normotensive females attenuated arterial hypertension with a tendency to normalization of the examined parameters. This confirms the possibility of modifying hypertensive phenotype by changing the conditions of the early postnatal development.

Animals↗
PubMed2001

Peculiarities of myocardial structure in rats with hereditary hypertension reared by normotensive females.

Morphometric analysis revealed no signs of myocardial hypertrophy at the tissue and ultrastructural levels in 3-week-old NISAG rat pups reared by normotensive Wistar females. The severity of myocardial hypertrophy in these animals aging 6 months was similar to that in NISAG rats reared by natural mothers. However, raising conditions during the early ontogeny form compensatory structural changes in the myocardium of rats with genetically determined hypertension.

Animals↗