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Biomedical subjects

B Ostádal

Publications and source records attributed to B Ostádal.

At least 91 records · Page 5Linked to original sources
PubMed1979

Developmental relationships between the structure, blood supply and metabolic pattern of the vertebrate heart.

In the animal kingdom there exist four types of myocardial blood supply: a) spongious musculature alone, which is supplied from the ventricular cavity; b) an inner spongious layer covered by an outer compact musculature with a vascular supply; c) as b), but with capillaries also present in some trabeculae of spongious musculature; d) compact musculature only, supplied from coronary vessels. The development of the compact layer in different species of cold-blooded animals is more closely related to heart weight than to the phylogenetic position of the animal; the total amount of compact musculature increases with increasing heart weight. These facts give additional support to the hypothesis that the development of compact musculature is necessary for the maintenance of balanced blood pressure conditions in larger hearts. The activities of enzymes connected with aerobic oxidation and glucose phosphorylation are higher in the spongious musculature than in the compact layer. The higher aerobic oxidative capacity of the spongious layer correlates with the higher sensitivity of this musculature to the necrogenic action of isoproterenol.

Animals↗
PubMed1978

Effect of intermittent high altitude hypoxia on the synthesis of collagenous and non-collagenous proteins of the right and left ventricular myocardium.

The incorporation of 14C-proline into collagenous and non-collagenous proteins of the right and left ventricular myocardium was investigated in rats exposed to intermittent high altitude hypoxia. Experimental results have shown that even in control animals significant differences exist in the concentration and synthesis of individual protein fractions between the right and left ventricular myocardium. Long-term exposure to intermittent high altitude hypoxia induced a significantly increased concentration of collagenous and non-collagenous proteins in both ventricles. The incorporation of 14C-proline was not affected at this period (ie period of stabilised hypertrophy) in either of the fractions studied.

Altitude Sickness↗
PubMed1977

DNA synthesis in the ventricular myocardium of young rats exposed to intermittent high altitude (IHA) hypoxia. An autoradiographic study.

Intermittent high altitude (IHA) hypoxia (7000 m) increased the wet weight of the right ventricular myocardium of 30-day-old rats after two 4 h/day exposures. During the same period the number of DNA-synthesizing nuclei of both muscle and non-muscle cell types increased proportionally. After 4 such exposures to hypoxia the number of 3H-thymidine-labelled nuclei in both cell types increased further. In addition, the number of labelled nuclei increased significantly in the yet un-enlarged left ventricle. While there was no difference in the number of DNA-synthesizing cells between the right and left ventricles in control animals, a significant increase in the number of cells involved in DNA synthesis in the right ventricle was found in both groups of animals exposed to IHA hypoxia. These results show that DNA synthesis in myonuclei of the ventricular myocardium can be stimulated in 30-day-old rats, i.e. at the very end of the weaning period.

Altitude↗
PubMed1977

Relative organ blood flow in rats exposed to intermittent high altitude hypoxia.

Circulating blood volume, cardiac output and relative organ perfusion changes were studied, using the Sapirstein method of 86RB tissue uptake, in male 75-day-old rats exposed to intermittent high altitude hypoxia (gradually up to 7000 m, 4 h daily, 5 days a week; the total number of exposures was 24). Intermittent hypobaric exposure caused a significant rise of the erythrocyte volume, whereas the plasma volume remained unchanged. The relative perfusion of the left and particularly of the right ventricular myocardium, as well as of the spleen, liver, lung, small intestine and skeletal muscle, was significantly higher. The cardiac output determined in other experimental animals similarly treated was significantly higher after 24 exposures to the intermittent high altitude hypoxia. We suggest that these changes are triggered by tissue hypoxia and a greater blood flow demand.

Adaptation, Physiological↗
PubMed1977

The development of myocardial changes during intermittent high altitude hypoxia in rats.

The initial phase and the development of myocardial focal necroses were studied in 50 rats adapted successively to intermittent high altitude. The altitude hypoxia was produced in a low pressure chamber (7000 m, five days a week, four hours daily). First-minute myocardial changes detected by histochemical methods were found after 4 exposures at a level of 3000 m and distinct ones after 8 exposures at a level of 4500 m. Histologically, acute focal necroses were found after 11 exposures at a level of 6000 m. Hypoxia and stress are suggested to account for these myocardial focal changes. During further adaptation no further acute focal necroses were observed.

Acid Phosphatase↗
PubMed1976

Structural and enzymatic properties of cardiac myosin in ischaemic and non-ischaemic regions of the rat myocardium.

In rats with ligation of the left coronary artery changes in ATPase activity and structure of cardiac myosin in both ischaemic and non-ischaemic zones of the myocardium were followed. In control animals, ATPase activity and the structure of the myosin molecule in right and left ventricles did not differ. Non-specific factors, such as anaesthesia and thoracotomy, can result in a decrease or an increase in ATPase activity respectively. One hour after ligation of the left coronary artery ATPase activity increased in the right, non-ischaemic myocardium and there was a significant right-to-left difference. Four hours after ligation, ATPase activity in both ventricles significantly decreased and the right-left difference disappeared. Within 48 h, normal values were found only in the non-ischaemic right ventricle. Ligation of the left coronary artery results after 48 h in the formation of structural alterations in cardiac myosin, primarily in the left, ischaemic myocardium. These changes are characterised by the formation of myosin aggregates, which have a significantly lower ATPase activity in comparison with monomeric myosin.

Adenosine Triphosphatases↗
PubMed1975

Experimental cardiac necrosis in hypobaric and anemic hypoxia.

Resistance to isoproterenol-induced cardiac necrosis (IPRO) was compared in rats exposed to two types of hypoxia (i.e., hypobaric and anemic). IPRO was induced by two consecutive, subcutaneous injections of isoproterenol (80 mg/kg) at 24-h intervals. The animals were killed on the third day and the severity of the lesion was evaluated on a 0 (no damage) to 4 (severely damaged) scale. White male rats (HA) were exposed in a barometric chamber to a simulated altitude of 7,000 m (307 mmHg) for 4 h/day for 24 days. Two groups of control rats were kept at sea level; one group (SLA) was the same age and one group (SLW) was the same weight as the altitude-exposed rats. The HA rats were significantly more resistant to IPRO with a mean necrogenic rating of 1.8 compared to 3.3 for the SLA and SLW rats. Infant rats (AA) were made anemic by feeding full-cream milk and glucose for 100 days after weaning. Two groups of control animals were fed a standard laboratory diet; one group (AC) was the same age and one group (AW) was the same weight as the AA rats. There was no significant difference in the necrogenic ratings of the AA (3.3), AC (3.5), or WC (3.7) hearts. Thus, hypobaric hypoxia affords some protection against IPRO which is not afforded by anemic hypoxia. Similarities and differences in the two hypoxias are discussed.

Anemia, Hypochromic↗
PubMed1975

Postnatal persistence of spongy myocardium with embryonic blood supply.

Focal presence of the embryonic pattern of myoarchitecture and of a lacunary blood supply was found in the left ventricular wall of five infant hearts. Four of these hearts showed various malformations; one was a case of cardiac fibroma. The persisting intertrabecular spaces and sinusoids communicated with the ventricular lumen; there appeared to be some communication with the coronary branches. The intertrabecular spaces of the spongy myocardium were lined with a continuous layer of endothelial cells, thus resembling the microscopical appearance of myocardium of adult cold-blooded vertebrates rather than the embryonic phase of myocardial development of warm-blooded animals.

Aortic Valve Stenosis↗
PubMed1975

Isoproterenol-induced necrotic lesions of embryonic heart tissue.

Chick embryos were used for analyzing the effect of isoproterenol on the embryonic heart. Isoproterenol (2 x 80 mg/kg in 48 hrs) was injected into the amniotic sac from the 5th embryonic day to the time of hatching. From the 5th to the 7th embryonic day (ed), transposition of great vessels occurs. From the 7th to the 14th ed, blockade of development of coronary vascularization was regularly observed, particularly in the ventral wall of the right ventricle. This effect is always associated with persistence of intertrabecular spaces in the nonvascularized area and with a higher water content in the heart. From the 10th to the 12th ed, degenerative changes of the cardiac musculature can be observed. Lesions were characterized by typical myolysis; capillaries in the affected area were dilated and blocked with packed erythrocytes. Necrotic changes were localized only in those parts of the ventricular walls where the vascular bed and myoarchitecture were normally developed. In comparison with similar changes in adult specimens, inflammatory cellularization is lacking.

Animals↗