Russian researchers advanced significantly in understanding the nature of atherosclerosis by studying how blood vessel disruption depended on various metal content in vessel walls. Experiments of chemical composition of atherosclerotic plaques revealed that zinc, previously considered to have great protective effect, was much less important than manganese.

Atherosclerosis is a chronic illness of arteries, which causes changes in their inner shell or intima. Lesions accumulate lipids, polysaccharides, and blood clots; connective tissue grows abnormally, and calcium compounds deposit. All mentioned processes lead to luminal occlusion (blood vessel narrowing), which in its turn, cause acute disorders of blood circulation, like infarctions (heart attack, for instance) or cerebrovascular accidents (blood strokes).

Medics and scientists have several theories, which explain how primary lesion (or nidus) is formed on a blood vessel wall. One of these theories suggests that low-density lipoproteins interact with metal atoms, which are contained in blood plasma, and these complexes precipitate on a vessel wall. This theory is confirmed by data on changes in metal content in blood vessel walls, connected with the disease’s progress. Vessels with walls, damaged by atherosclerosis, contain more calcium, iron, copper and zinc, than vessels of healthy person. Apparently, calcium, iron and copper have so-called atherogenic effect, in other words, these metals promote atherosclerosis development. As for zinc, it has anti-inflammatory effect and protects vessel walls from being damaged.

 

 

By now the role of manganese in processes of precipitation of lipoproteins on vessel walls remained questionable. The only thing researchers knew was that this metal was essential for synthesis of an important antioxidant enzyme, called manganese superoxide dismutase. Lack of manganese causes malfunctions of mitochondria in vessel walls, which is a characteristic feature of early stages of atherosclerosis.

Researchers from Kazan State University together with their colleagues from Kazan Interregional clinicodiagnostic laboratory have estimated concentration of manganese, copper, zinc and iron in atherosclerotic plaques with various level of calcification (this level usually depends on calcium-phosphorus level). The research was conducted on 10 samples of human aortal tissue, damaged by atherosclerosis. These samples were carefully purified by chemical means, as well as in vacuum under temperatures below zero Centigrade. Data on metal concentrations were obtained by means of a mass-spectrometer.

The experiment revealed new patterns in metal distribution in vessel walls, depending on how massive pathological changes in aorta were. Scientists showed correlation between zinc and calcium concentration in atherosclerotic plaques – this discovery contradicts with general concept of zinc as an anti-atherogenic agent. Furthermore, scientists discovered a strong negative correlation between level of calcification and the amount of manganese in vessel wall, which means lack of manganese promotes atherosclerotic damage of blood vessels. Researchers believe that manganese concentration may become and important marker for estimating the level of damage, caused by atherosclerosis.

Source: Science News

Kizilova Anna