Cholesterol plays a critical role not only in modulating membrane structure and dynamics but also in its metabolic pathway, to interfere with cell growth and proliferation processes. Having this aim in mind, we have suggested an investigation, by radioisotopic techniques, of the effect of vitamin E (alpha-tocopherol, 3 mg/kg b.w. in daily doses, for 7 days) on the unscheduled DNA biosynthesis, induced by Romanian cytostatic Lomustin (Nipalkin or CCNU at the dose of 10 mg/kg b.w in acute administration, for 24 h), both on normally fed animals and on rats having a hypercholesterolemic diet, for 30 days. Considering the scientific data from the literature, according to which there is an inverse correlation between the serum cholesterol level and the risk of developing cancer, we tried to investigate the possible influence of Wistar rat cholesterolemic background on the nuclear unscheduled DNA biosynthesis, essential for the conservation of the cell genome integrity. So, it has been noticed that: 1) the DNA lesions induced by the alkylant and tested by the uptake of 3H-Thymidine (200 microCi/100 g b.w.) are reduced after vitamin E treatment, suggesting a protective effect of the antioxidant on the genetic material. 2) on a hypercholesterolemic background the administration of Lomustin produces a decrease of cholesterolemia, suggesting the development of a "facilitating environment" for CCNU action, which appears to confirm the data from the biographical sources. 3) using 3H-Cholesterol (150 microCi/100 g b.w.) to estimate its intracellular liver incorporation suggests a possible displacement of cholesterol from the tissue compartment to the serum one and reverse, event which appears to be correlated with unscheduled DNA biosynthesis. This sustains the idea of the intracellular cholesterol necessity during the nucleic acid biosynthesis as well as in genome aggression.

Animals↗

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Na+ and K+ dependent ATP-ase and structural modifications in hypokinetic rats.

In rats the hypokinetic state obtained by restraint in special cages, produces after 30 days, a marked decrease in Na+ and K+ dependent ATP-ase in the skeletal muscle. After 15 days hypokinesia the enzymatic content of the investigated tissues did not change. In the left cardiac ventricular muscle Na+ and K+ dependent ATP-ase decreased after 15 days and particularly after 30 days hypokinesia. These changes were brought about by the hypofunctional state of both muscles, which also produced structural alterations. In the skeletal and cardiac muscles electron microscopy revealed fibrillar atrophy and mitochondrial alterations typical of an affected function. In the cardiac muscle, in which these changes were more accentuated, the dissociation of the intercalar disc was also noted, aspects partially described by others.

Adenosine Triphosphatases↗

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Proofs concerning the existence, in the blood of hypertensive patients, of some serum factors influencing the vascular smooth muscle and the myocardium physiology.

Starting from the existence of some autoimmune diseases (i.e. bronchial asthma or miastenia gravis) we asked ourselves if some plasmatic factors do exist, influencing the receptor--mediator relations in cardiovascular system during some illnesses having unknown etiology, as arterial hypertension. For this reason, in this work was tested the hypothesis that, in some chronic cardiovascular diseases would exist factors circulating and affecting the functions of the cellular membranes of the arterial wall, particularly of the smooth muscle cells and myocardial cells. Our results show a significant modification of the calcium fluxes and of some neuromediators uptake at the hypertensive patients.

Animals↗

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Na+--K+ dependent ATP-ase in skeletal muscle and left ventricular myocardium in rats submitted to movement restraint and a recovery period.

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Animals↗

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The effects of adrenaline on the rat isolated arteriolar wall.

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Animals↗

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The effect of +Gz acceleration upon lactate, pyruvate and some nucleotides in the nervous tissue of the guinea pig.

The present paper was designed to the study of the effects of hypoxia induced by positive accelerations upon energy metabolism in the brain. Variations in the amount of lactate, pyruvate, ATP, ADP and AMP were determined immediately after centrifugation and after intervals of 30 to 90 minutes. An increase in the quantity of lactate and pyruvate, and a diminution of ATP running parallel to an increase in AMP were noted immediately after centrifugation. These variations almost entirely disappeared 90 minutes after centrifugation. These findings drew attention to a possible imbalance of the neuronal energy processes, which might bring about, even for short periods, alteration of the neuronal function.

Acceleration↗