Age-related characteristics of capsular angioarchitectonics of large human joints

Angioarchitectonics of 127 capsules of large joints in superior (brachial, ulnar, radiocarpal) and inferior (coxofemoral, genicular, talocrural) extremities have been studied using a complex of anatomical and histological techniques and morphometry. As demonstrate the investigations, in the fibrous and synovial membranes of the capsules in these joints, there are certain differences in the architectonics and in depth of the blood network arrangement. In accordance with the diameter of these vessels, density and character of distribution in the capsule membranes of the joints, it is possible to distinguish four circulatory networks. They have numerous anastomoses and form a united volumetric network of vessels. Certain general regularities are noted in the structure of the vascular networks of the capsule membrane in the extremity joints, as well as changes of their angioarchitectonics are revealed as adaptations to age morphofunctional changes in the connective tissue formations of the capsules.     

Age-related characteristics of intraorganic vascular structures of the cerebral cortex, heart, kidneys and spleen in rats in the normal state and in arterial hypertension

The work has been performed on 40 normotensive and spontaneously hypertensive rats at the age of 6 months-1 year. In all the organs studied a direct dependence between the degree of changes in the intraorganic arterial walls and a relative content of the arterial vessels in the organ tissues has been revealed. The functional changes of the arterial bed of the organs mentioned in spontaneously hypertensive rats during hypertensive phase at the stage of stable hypertension, as a result of a prolonged adaptation transform into organic ones.     

Age-related arterial calcification in rats

In man, i) arteries calcify with age and ii) age-linked arterial calcification is amplified by vascular pathology such as hypertension or arteriosclerosis. Age-linked arterial calcification has a bad prognosis but drugs to prevent it are lacking. This is partially due to the lack of appropriate animal models. This paper looks at the extent to which arteries calcify with age in the rat and whether hypertension or arteriosclerosis amplifies such calcification. Total calcium levels were determined by acid digestion and flame spectrophotometry and intracellular calcium levels ([Ca2+]i) by the intracellular calcium-sensitive dye, fura-2. Arteries contained up to 5 times more calcium than other soft tissues. Arteries progressively calcified with age whereas other soft tissues did not. Accumulation of calcium with age was essentially extracellular. Hypertension had no effect on age-related arterial calcification. Calcification of the same order as in man was produced in a rat model of arteriosclerosis (vitamin D plus nicotine treatment). In conclusion, as in man, age-linked, organ-specific arterial calcification does occur in rats but its intensity is far less. Arterial calcification of a similar degree to that observed in man can be obtained in rats by hypervitaminosis D plus nicotine.     

Age-related structural and functional characteristics of cardiac myoendocrine cells of rats in a normal state and with hereditary hypertension

A qualitative and quantitative ultrastructural study of right atrial cardiomyocytes in WAG (normotensive control) and ISIAH (inherited stress-induced arterial hypertension) rats of different age (on day 18 of embryogenesis, on days 12 and 21 after birth, and at an age of 6 and 13 months) was performed. It was shown that, in embryos with an as yet incomplete atrial morphogenesis, secretory granules containing natriuretic peptides are actively formed, accumulated, and dissolved. In postnatal ontogeny, the secretory product is accumulated in atrial cells. In all ontogeny stages studied, the numerical density of secretory granules in the myoendocrine cells of hypertensive rats is greater and the qualitative composition of these granules is more diverse than in the control. It was established that, in atrial myocytes of ISIAH rats, the morphological signs of natriuretic peptide hypersecretion precede the development of genetically programmed high blood pressure. In adult hypertensive rats, hypertrophic and degenerative changes in myocytes are accompanied by excessive accumulation of secretory granules, some of which undergo intracellular degradation.     

Age-related growth of the spleen in normal and glucocorticoid treated rats

1. Age-related changes in the growth, nucleic acid content and protein turnover of the spleen have been studied in normal male rats. 2. A rapid and marked atrophy of the spleen, was found 24 hr after exposure to cortisone or dexamethasone; increased rates of protein breakdown being primarily responsible. 3. Nonetheless, the total amount of protein synthesized in the spleen (measured in vivo) was significantly decreased (30-50%) 24 hr after exposure to these steroids. 4. This compared with only a 15% decrease in whole body protein synthesis, indicating a more pronounced hormonal effect on the spleen than on most other body tissues.     

Morphofunctional characteristics of cadmium-induced arterial hypertension

Chronic (12 weeks) peroral administration of cadmium chloride to albino rats in a dose of 2.5 mg/100 g body weight results in arterial hypertension characterized by the increase in systolic blood pressure up to 148 +/- 1.8 mm Hg (vs. 115.4 +/- 1.5 mm Hg in the control animals); the increase in vascular resistance, left ventricular cardiomyocyte hypertrophy, as well as by hypertrophy of arterial walls, the decrease in the ventricular index, the activation of synthesizing function of atrial endocrine cardiomyocytes; enhanced secretion of ANP; a more than two-fold increase in plasma myoglobin concentration, as well as by the development of cadmium-induced nephropathy. In the rehabilitation period (9 weeks) a relatively quick fall in the blood pressure is observed, as well as morphological features of myocardial and renal function recovery, suggesting the nonpersistent nature of cadmium-induced hypertension.     

Morpho-functional characteristics of the mast cells of the subcutaneous connective tissue in rats with arterial hypertension

Mast cells of the rat subcutaneous connective tissue were studied in experimental hypertension. An increase was discovered in the degranulation of the cells in rats with spontaneous and adrenal-regenerative hypertension. These animals demonstrated a rise in the number of immature cells with a relatively low content of serotonin. The changes described are believed to be linked with arterial pressure elevation.     

Age-related characteristics of the activity of phagocytes in the normal state and in infections

Activity of peroxidase (AP) and maintenance of lysosomal cation proteins (CP) were studied during phagocytic reaction of polymorphonuclear leukocytes of healthy persons of different age and those with acute respiratory disease and chronic tonsillitis. It is found that during acute virus and chronic bacterial infection similar changes in AP and CP dynamics are observed, which is correlated with a decrease of phagocytic digesting function.     

Age-related growth and protein turnover in the thymus of normal and glucocorticoid-treated rats

Possible derivatives of the amino acids tryptophan, tyrosine and histidine were examined as to their effect on protein metabolism in isolated rat hepatocytes. One of the substances tested, kynurenine (a main product of the catabolism of tryptophan), might be a physiological regulator of the lysosomal degradation of endogenous protein, because of the following. (a) Kynurenine decreased the lysosomal (i.e. methylamine-sensitive) pathway of degradation to a much greater extent than its parent amino acid, without interfering with the non-lysosomal pathway. (b) Kynurenine did not appreciably reduce the (lysosomal) degradation of the endocytosed protein asialo-fetuin, or the rate of protein synthesis, indicating a specificity of action. (c) Electron micrographs revealed a reduction in secondary lysosomes due to kynurenine.     

Age-related and organ-tissue characteristics of the function of the antioxidant system in white rats

Various components of antioxidant system (concentration of the reduced and oxidated forms of non-protein thiol compounds and ascorbic acid, the activity of glucose-6-phosphate dehydrogenase, glutathione reductase, catalase, superoxide dismutase) have been investigated in the blood, brain and liver of growing albino rats. It was found that the specific condition of this system depends on the age of animals and on the source of the system. Disorganization of the antioxidant system in senile animals was noted which results from intensification of free radical oxidation.     

Endocrine-metabolic relations in rats with genetic arterial hypertension

Levels of triiodothyronine, thyroxine, insulin, glucose and free fatty acids in the blood; contents of adrenaline, noradrenaline in adrenals and glycogen in the liver; activity of phenylethanolamine-N-methyltransferase in adrenals, hexokinase and glucose-6-phosphatase in the liver were studied in male Wistar rats and rats with inherited stress-induced arterial hypertension /ISIAH/. It was found that genetically caused rise of hypophyseal-thyroid systems activity in ISIAH-rats leads to a decrease of insulin blood level, activation of lipolysis and breach of glucose tolerance.     

Reactivity of the hypothalamo-pituitary-adrenocortical system in rats with hereditary arterial hypertension

The function of hypothalamo-hypophyseal-adrenocortical system was studied in rats with inherited stress-sensitive arterial hypertension (ISSAH). The rats have been bred from the outbred Wistar strain. It was found that plasma corticosteroid level in ISSAH rats was lower after immobilization stress and higher after stress induced by a combination of stress-factors (ether, 0.7 ml blood loss, novel situation), as compared to Wistar rats. ISSAH rats also showed a reduced reaction to intracerebroventricular noradrenaline (10 micrograms) injection. It was concluded that the changes of noradrenergig brain mechanisms can be responsible for the alterations in the central regulation of blood pressure and adrenocortical function in ISSAH rats.     

Characteristics of the central adrenergic mechanisms regulating arterial pressure in rats with hereditary arterial hypertension

Adrenergic mechanisms of blood pressure regulation were studied in a newly developed strain of rats with inherited stress-provoked arterial hypertension, spontaneously hypertensive rats (SHR) and normotensive Wistar rats. A number of adrenergic agonists (noradrenaline, adrenaline, phenylephrine, clonidine, naphazoline, isoproterenol, dobutamine, Alupent) were infused into the lateral brain ventricle under nembutal anesthesia and the reaction of the peripheral blood pressure was measured. It was shown that blood pressure reactions were similar in rats with inherited stress-provoked arterial hypertension and in SHR but significantly differed from those of normotensive Wistar rats. The data obtained suggest that the development of inherited hypertension was accompanied by changes in alpha 1 to alpha 2 adrenoreceptor ratio in pressor and depressor brain regions. A decrease in the depressor effect after stimulation of beta 1 and beta 2 receptors has been also observed.     

Somatosympathetic reflex in rats with various models of arterial hypertension

Spontaneous and reflex activities of sympathetic nerve were compared in animals with arterial hypertension of different aetiology. Reflex discharges elicited by single-shock stimulation of afferent fibres were recorded. In acute experiences on anaesthetized rats with renovascular and spontaneous (SHR) model of arterial hypertension, electric basal and evoked activity (somatosympathetic reflex) in cervical sympathetic trunk were recorded. It is shown, that the spontaneous electric activity in sympathetic nerve of hypertensive rats is larger than spontaneous activity of normotensive control animals. The somatosympathetic reflex in hypertensive rats differs from that of control animals. In rats with renovascular model of hypertension, the reflex magnitude is reduced, and in the SHR the reflex is increased. Time characteristics of the reflex in hypertensive rats differed among them. It is suggested that functional activities of the brain stem in rats with different arterial hypertension model are unequal.     

Compliance characteristics of the hind-limb arterial system of normal and hypertensive rabbits

Pressure transients resulting from square-wave changes in abdominal aortic blood flow rate were used to derive effective arterial compliance and peripheral resistance of the hind-limb circulation of anaesthetized rabbits. The model for deriving these parameters proved applicable if step changes in flow were kept less than 35% of mean flow. Under resting conditions, the effective hind-limb arterial compliance of normal rabbits averaged 3.46 X 10(-3) mL/mmHg (1 mmHg = 133.322 Pa). Hind-limb arterial compliance decreased with increasing pressure at low arterial pressures, but unlike compliance of isolated arterial segments, compliance did not vary at and above normal resting pressures. Baroreflex destimulation (bilateral carotid artery occlusion) caused an increase in effective hind-limb vascular resistance at 48.4% and a decrease of arterial compliance of 50.7%, so that the constant for flow-induced arterial pressure changes (resistance times compliance) was largely unchanged. Similarly, the arterial time constant for rabbits with chronic hypertension was similar to that for controls because threefold increases in hind-limb vascular resistance were offset by decreases in compliance. Reflex-induced decreases in arterial compliance are probably mediated by sympathetic nerves, whereas decreases associated with hypertension are related to wall hypertrophy in conjunction with increased vasomotor tone. Arterial compliance decreased with increasing pressure in hypertensive animals, but this effect was less pronounced than in normotensive rabbits.     

Expression of the pro-opiomelanocortin gene in rats with inherited arterial hypertension]

Expression of pro-opiomelanocortin (POMC) gene in pituitary of rats from newly developed hypertensive strain (ISIAH strain) was studied by dot hybridization. The pUC8 plasmid containing 900 base pair (bp) segment or the human POMC gene corresponding to the major portion of the 3'-nontranslated mRNA region and 60 bp coding for the signal peptide, was used as a probe for hybridization. It was found that the expression of the POMC in pituitary of the hypertensive JSJAH rats was more than 3-fold gene lower as compared to normotensive Wistar strain. The latter is the original strain from which the ISIAH rats were bred. The mechanism of this phenomenon and its possible relation to the arterial hypertension are discussed.