PubMed Health⌕ Search

Biomedical subjects

V V Frolkis

Publications and source records attributed to V V Frolkis.

At least 37 records · Page 2Linked to original sources
PubMed1988

Contractile function and Ca2+ transport system of myocardium in ageing.

Experiments with animals with various species-specific life span (rats, rabbits, cats, dogs) and different models (in situ heart, isolated perfused heart, isolated papillary muscle) have proved the reduction of functional capacity of the ageing heart. Diversely directional age-dependent shifts have been established involving myocardial Ca2+ transport system, i.e. an increase in the rate of Na+-Ca2+ exchange and passive Ca2+ transport across sarcolemma and a decrease in its Ca2+-binding capacity and a decrease in Ca2+ accumulation by sarcoplasmic reticulum and mitochondria (Ca2+ uptake). The experiments revealed a decrease in the Ca2+ ATPase myosin activity in the myocardium of aged animals and absence of age changes in the K+ ATPase activity. The findings obtained suggest that the development in the cardiac contractile function disorders in ageing largely depends on the age-related changes in the Ca2+ transport system.

Aging↗
PubMed1987

Antioxidants as antiarrhythmic drugs.

Experiments on rats and rabbits using models of arrhythmias induced by vasopressin, epinephrine, strophanthin, and CaCl2 showed that antioxidants derived from 1,4-dihydropyridines, dibunol, and alpha-tocopherol possessed antiarrhythmic effects. Administration of these antioxidants decreased the occurrence of extrasystoles, disturbances of atrioventricular conductivity and ventricular fibrillation. These drugs also prevented changes in membrane phospholipid composition, inhibited activation of peroxidation, decreased phospholipase activity, prevented a decrease of Ca2+ ATPase and Ca2+ binding and uptake by sarcoplasmic reticulum, and increased sarcolemmal Na+, K+-ATPase, sarcoplasmic reticulum creatine phosphokinase.

Animals↗
PubMed1985

Axoplasmic transport of substances in motoneuronal axons of the spinal cord in old age.

Seven to eight microliters of aqueous solution of L-[14C]Leucine (spec. act. 339 mCi/mmol) were introduced in the zone of ventral horn (L5-L6) of the spinal cord of adult (8-12 months) and old (26-28 months) rats. The radioactivity of various parts of the corresponding ventral roots was measured 1-2.5 h thereafter. Labelled substances (including protein) were found to migrate with fast flow in adult rats at the rate of 408 +/- 10.9 and 380 +/- 22 mm/24 h, respectively, as compared with 217 +/- 11.3 and 200 +/- 40 mm/24 h in old rats. The axoplasmic flow slows down in old rats with the increase of distance from the neuronal body. Uncoupling of oxidation and phosphorylation by the administration of 2,4-dinitrophenol, inhibition of glycolysis with NaF, hypoxemia produce more marked deceleration of axoplasmic flow in old rats, while small doses of NaF accelerate the flow, which correlates with the rise of cAMP in ventral roots. Sex steroids accelerate significantly the rate of axoplasmic flow. There is a marked increase in the rate due to the administration of estradiol dipropionate in old rats and due to testosterone propionate in adult animals. Changes in resting membrane potential and direct excitability thresholds of some muscles following colchicine blockade of axoplasmic transport are less marked in old rats that evidences for the weakening of neurotrophic control in old age.

2,4-Dinitrophenol↗
PubMed1985

Regulation of aldosterone secretion in old rats.

The experiments on adult (4-6 months) and old (28-30 months) rats revealed changes that develop in old age in various links of the regulatory system of aldosterone secretion: the hypothalamic-hypophyseal control of mineralocorticoid secretion decreased, and the sensitivity of the glomerular zone to ACTH, vasopressin, and K+, as well as that of the myocardium, skeletal muscle and kidney to aldosterone increased. Changes in tissue sensitivity to aldosterone may be due to the increased affinity of mineralocorticoid receptors to aldosterone in old age.

Adrenal Cortex↗
PubMed1984

Enterosorption in prolonging old animal lifespan.

The effect of repeated courses of enterosorption upon the mean and maximal lifespan and some functional and metabolic indices was determined in 28-month-old Wistar rats. Significant increase of mean and maximal lifespan of old rats was noted at certain regimens of enterosorption. The experimental animals demonstrated less marked age-related structural and ultrastructural changes in the liver, kidneys, myocardium, intestines, pancreas, as compared with control animals. Enterosorption leads to a reduction of pentobarbital-induced sleep, decrease of content of cytochrome P-450, blood cholesterol and triglycerides, cardiac and cerebral tissue cholesterol, total lipids, liver cholesterol and triglycerides. Enterosorption was found to increase the RNA and protein biosynthesis in the liver, kidneys and adrenals of old animals.

Aging↗
PubMed1982

Vasopressin and cardiovascular system in aging.

The studies concerned age-dependent peculiarities of the vasopressin effect on the hemodynamics and tone of the coronary vessels in dogs, the contraction of the isolated vascular strip in rats, and the hemodynamic and ECG indices in rabbits and in rats. The data obtained indicate the great sensitivity of old vessels to vasopressin. In aging, both humans and animals show a rise of vasopressin concentration in the blood. Age-dependent differences of the vasopressin effect on the kallikrein-kinin system, adenosine metabolism, the contents of prostaglandins and cyclic AMP have been established. High sensitivity to vasopressin in combination with its increased concentration in the blood is an important factor that contributes to the development of arterial hypertension and ischemic heart disease.

Adenosine↗
PubMed1980

Kallikrein-kinin system and adenosine metabolism system of blood and heart and their changes at hypothalamic-hypophyseal stimulation in rabbits of different age.

It was shown that kallikreinogen content was decreased in blood of old rabbits, kallikrein activity was somewhat increased, kininase activity was significantly decreased. In old animals, adenosine metabolism was activated, this being evident from the rise of 5'-nucleotidase and adenosine deaminase activity in blood and myocardium. Hypothalamic stimulation resulted in significant activation of the kallikrein-kinin system and sharp increase of kallikrein activity, the shifts being less marked in old animals than in adults. In adult animals, vasopressin administration elicited more marked activation of the kallikrein-kinin and adenosine metabolism systems.

Adenosine↗
PubMed1979

Mechanisms of neurohumoral regulation of heart function in aging.

Changes in hemodynamics and myocardial contractile capacity following the stimulation of extracardial nerves and administration of various doses of acetylcholine, norepinephrine, propranolol, phentolamin, atropine, serpasil and benzohexonium were studied in albino rats, rabbits and cats of various age. The shifts in cardiac acetylcholine and norepinephrine content and the activity of some enzymes of their catabolism were determined as well. Functional changes were compared with the structural shifts in intramural nervous system. In old animals there was a rise in threshold of voltage, which induced threshold reaction at stimulation of n. vagus and n. sympaticus and there was a change in heart sensitivity to acetycholine and norepinephrine, propranolol, atropine, serpasil and benzohexonium. A relationship was shown between age changes in nervous regulation of heart and transmitter metabolism. The intensity of acetylcholine and norepinephrine synthesis was decreased in old age, the transmitter metabolism in various parts of the heart was not uniformly altered, the sensitivity of epicardial chemoreceptors to nicotine, veratrum, acetylcholine was increased. The reflexes from cardiac mechanoreceptors were diminished.

Acetylcholine↗
PubMed1978

Metabolism of thyroid hormones during aging.

The paper presents experimental data on extrathyroidal metabolism of thyroid hormones in rats of various ages (1.5--32 months):: T4-131I distribution in an organism, indices of T4 and T3 kinetics, tissue deiodinative capacity, formation of T4 tissue metabolism products and their clearance from cells and organism, T4 binding with tissue proteins. Essential changes in T4 peripheral tissue metabolism have been found with aging: T4 binding by tissues is decreased; T4 distribution space and metabolic clearance are increased; 125I clearance with urine is decreased; T4 half-time in blood remains unchanged; tissue deiodinative capacity is enhanced. Indices of T3 peripheral metabolism in old rats remain unchanged. All these findings result in shifts of the T4/T3 ratio in favour of the latter and in invariability of its content in tissues, alongside with a decrease of functional activity of the thyroid gland with aging.

Aging↗
PubMed1976

Aging of the neuromuscular apparatus.

With age marked changes in metabolism and function of muscle fibers appear: electroexcitability thresholds rise, critical polarization level and membrane resistance decrease, time of action potential increases and its amplitude decreases, lability is reduced. The level of intracellular sodium increases and that of potassium decreases. Shifts in ionic asymmetry of muscle fibers are connected with changes in their membrane permeability and a modified function of the sodium-potassium pump. Along with the impairment of nervous influences on muscle fibers in old age, their sensitivity to many hormonal factors increases. Loading levels all age differences in the regulation of skeletal muscle vascular tone. The relationships between the activity of the genetic apparatus and electrical properties of the cell are altered.

Aging↗