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Biomedical subjects

J Mourek

Publications and source records attributed to J Mourek.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effect of vanadate on (Na+-K+)-stimulated ATPase activity in the brain of rats of different ages.

Experiments were carried out on infant rats aged five days and on adult rats (of both sexes) to investigate vanadate inhibition of (Na+-K+)ATPase activity in various parts of the brain. Vanadate was administered in 10(-5), 10(-7), 10(-8), 10(-9) and 10(-10) mol/l concentration. The enzyme activity and the effect of vanadate were studied in the tissue of the cerebral cortex, subcortical formations and the medulla oblongata. It was demonstrated that an inhibitory effect of vanadate on ouabain-sensitive ATPase could be determined in the brain of very young rats, i.e. in the immature nervous tissue. It was further demonstrated that the inhibitory effect of vanadate (in low concentrations) was significantly more potent in the nervous tissue of adult rats than in the CNS tissue of 5-day-old animals. Lastly, attention is drawn to certain differences in the sensitivity of ouabain-sensitive ATPase to the action of vanadate indifferent parts of the CNS in both the given age groups.

Animals↗
PubMed1987

Fatty acid values in the plasma of neonates, umbilical cord and maternal blood.

The proportion of a wide range of fatty acids was studied in the plasma of 15 healthy newborn infants following a physiological pregnancy and delivery. The same measurements were done in seven healthy mothers (immediately after parturition) and the proportion of fatty acids was analysed in mixed umbilical cord blood (n = 7). The fatty acids were identified by gas chromatography as their methyl esters (FAME). In newborn infants the proportion of saturated fatty acids was found to be 42.3%, of monoene fatty acids 31.3% and of polyene fatty acids 25.4%; type n-6 fatty acids formed 13.9% and n-3 11.1%. The proportion of the various fatty acids in healthy maternal plasma was 37.9% (saturated), 34.4% (monoene) and 25.0% (polyene) respectively; type n-6 fatty acids formed 21.6% and type n-3 only 3.6%. The values in mixed cord blood were 44% (saturated FA), 34.8% (monoene FA) and 20% (polyene FA); group n-6 FA accounted for 17.4% and n-3 for only 2.1%. In the above three series we also described the sequence of the fatty acids present in the largest amounts. This is part of an extensive study, in a large series, of the commonest perinatal risks. We particularly draw attention to the high proportion of long-chain fatty acids (C 22 - C 26) in the plasma of healthy newborn infants.

Fatty Acids↗
PubMed1986

Effect of acute altitude hypoxia on fatty acid proportion in the plasma of rats of different ages.

Using gas chromatography, the authors studied the development of the proportion of 25 saturated and non-saturated fatty acids in the plasma of Wistar rats of their own breed aged 5, 10, 14 and 25 days and adult (both sexes), and in three age groups (5 and 14 day and adult) they determined the effect of acute altitude hypoxia. Fatty acids were determined as methylesters (FAME) (Base 1978), using the method already described by Smídová et al. (1984a), in mixed blood plasma obtained from decapitated control and experimental animals. Altitude hypoxia, which corresponded to 9 000 m, lasted 20 min. The temperature was kept stable at 25 degrees C. Marked changes occurred during ontogenesis in the proportion of total fatty acids (TFA) in the plasma; the proportion of sigma non-saturated FA fell significantly during maturation, chiefly in favour of monoene FA, with a resultant significant drop in their reciprocal index (sigma saturated/sigma monoene). The proportion of all saturated FA amounted in 5-day-old rats to 54% of the total quantity, but in adult rats to only 40%. Acute hypoxia had a demonstrable effect in all three age categories. In 5-day-old rats it led to significant changes in 7 FA and in adult rats in 10. In both 5-day-old and adult animals it produced an increase in the arachidonic acid level. The results are discussed in relation to previous findings on the effect of the same hypoxia on FA proportion in various parts of the CNS of rats of different ages.

Aging↗
PubMed1986

Effect of hypoxia and short-term fasting on the plasma acetoacetic acid level in rats of different ages.

The acetoacetic acid level in rat plasma was studied by Walker's method (Walker 1954) during ontogenesis, after 20 min exposure to altitude hypoxia (7,000 or 9,000 m) or after short-term (24 h) deprivation of food and water. Wistar rats of both sexes, bred at the authors' department, were employed. The results confirmed earlier findings on the acetoacetic acid level during ontogenesis (Drahota et al. 1963) in addition, it was found that the level of the given acid in the rats' blood fell steadily during the whole of the pre-weaning period. Short-term deprivation of food and water significantly raised the plasma acetoacetic acid level in 5- and 10-day-old and adult rats; the maximum absolute increase was found in the youngest age groups. Hypoxia corresponding to 7,000 m significantly raised the plasma acetoacetic acid level in 5- and 10-day-old rats, but not in adult animals. Hypoxia corresponding to 9,000 m raised it significantly in 5-day-old animals only. We associate these findings with the possible utilization of acetoacetic acid, as a suitable energy substrate, by certain tissues, in particular the tissues of the CNS, in the youngest organisms.

Acetoacetates↗
PubMed1986

Development of resistance of the outer membrane of brain and liver mitochondria.

The outer membrane resistance of brain and liver mitochondria to the action of digitonin was studied in 5- and 60-day-old rats. Disintegration of the outer membrane was evaluated by means of cytochrome oxidase activity. The mitochondria were isolated by the Ficoll gradient method. Brain mitochondria were found to be significantly more resistant to digitonin than liver mitochondria. It was also demonstrated that the resistance of the outer membrane of both brain and liver mitochondria rose approximately 1.3- to 1.4-fold during ontogenesis.

Age Factors↗
PubMed1985

Oxidation of acetoacetate and palmitylcarnitine by brain and liver mitochondria from suckling and adult rats.

Experiments in which we investigated the possible oxidative utilization of lipoid substrates by brain and liver mitochondria were carried out with rats aged 5 and 90 days, kept under completely standardized conditions. Brain mitochondria were isolated on a Ficoll gradient after Clark and Nicklas (1970). Respiratory activity (or the respiratory control index-R.C.) was determined in the manner described in an earlier paper (Dobesová and Mourek 1980). Na succinate or Na malate was used as the testing substrate; palmityl carnitine, acetyl carnitine and acetoacetate were used as lipoid substrates. Oxygen consumption was measured with a Clark's oxygen electrode and respiration was expressed in nAt oxygen per min per mg protein, which was measured by the method of Lowry et al. (1951). When using succinate or malate, in agreement with our previous results we did not find any development changes in the respiratory activity of the brain mitochondria. The oxidation of acetoacetate by the brain mitochondria of 5-day-old rats was about five times greater, and of acetyl carnitine over two times greater, compared with the CNS mitochondria of adult rats. The oxidative utilization of lipoid substrates by the liver mitochondria of 5-day-old rats was significantly greater than their utilization by CNS mitochondria (in the case of palmityl carnitine three times greater, for example) and was always significantly greater than in the liver mitochondria of adult rats. We demonstrated that mitochondria isolated from the brain of 5-day-old rats are equipped with an enzymatic apparatus which allows them to utilize lipoid substrates on a significantly greater scale than in adulthood.

Acetoacetates↗
PubMed1984

Developmental fatty acid changes in different parts of the rat brain.

The proportion of 26 fatty acids (FA) in the lipids of the cerebral cortex, subcortical formations (the thalamus, hypothalamus and basal ganglia) and the medulla oblongata was studied in rats aged 5, 10, 14 and 90 days. Very marked developmental changes in the proportion of the various FA were demonstrated in the different parts of the brain. In the cerebral cortex the proportion of 17:1 rose by 285%, 18:3 n-3 by 1820% and 22:6 n-3 by 80%, while the proportion of 14:0, 16:0 and 16:1 fell significantly. In the tissue of subcortical formations we found an increase in the proportion of FA with 18 carbons (18:0 by 40%, 18:1 by 100%, 18:3 n-3 by over 5000%) and a decrease in the proportion of 14:0, 16:0, 16:1 and 20:4 n-6. The situation in medulla oblongata tissue was similar to the one in subcortical formations. On comparing the proportion of FA in individual parts of the CNS in the same age category, we found the smallest number of statistically significant differences in 5-day-old rats. In adult rats we found significant differences chiefly in the proportion of palmitic acid (16:0), oleic acid (18:1), linolenic acid (18:3 n-3) and acids with 20-22 carbons.

Aging↗
PubMed1982

Responsiveness of the trimmed rat subcutaneous adipose tissue beta-receptors to catecholamines in ontogenesis.

In order to estimate the possible changes of the functional state of beta-adrenergic receptors during ontogenesis, the lipid mobilizing effects of isoprenaline (ISO), adrenaline (ADR) and noradrenaline (NA) were studied in trimmed subcutaneous adipose tissue of rats at different stages of postnatal development (5, 14, 21 and 35 days after birth. The release of free acids (FFA) into the incubation medium was measured after addition of increasing concentrations of catecholamines and the dose-response curves were evaluated. In all the studied age groups, ISO produced the highest maximum effect and had the greatest potency. The calculated pD2 values indicate the same potency order ISO much greater than NA = ADR in all age groups and they also demonstrate that there exist no appreciable differences in the affinity single catecholamines at different stages of postnatal development. In comparison with all the other groups, the intrinsic activity of the studied adrenomimetics was relatively low in 14-day-old rats.

Adipose Tissue↗