Uloge endotelina u kardiovaskularnoj fiziologiji i patofiziologiji od njegovog otkrića do danas su neosporne. U srcu endotelini su značajni za procese razvoja, rasta i remodelovanja kao i za kontrolu kontraktilnosti i ritmičnosti. Srčane endotelne ćelije u endokardu i miokardnim kapilarima predstavljaju glavni izvor endotelina, a kardiomiociti su njihova primarna meta. Endotelin-1 je jedna od najpotentnijih poznatih supstanci sa pozitivnim inotropnim efektom, stoga endotelini imaju ključnu ulogu u srčanoj endotelno-miokardnoj interakciji. Endotelini su familija peptida od 21 amino kiseline koju čine endotelin-1, endotelin-2 i endotelin-3. Ostvaruju svoje efekte aktivacijom endotelinskih receptora, ETA i ETB, koji pripadaju familiji receptora vezanih za G proteine. ETA i ETB receptori su gusto distribuirani na kardiomiocitima, ćelijama provodnog sistema srca, koronarno vaskularnim i endokardno endotelnim ćelijama. U fiziološkim uslovima mesto sinteze endotelina su endotelne ćelije ali u patofiziološkim uslovima i veliki broj neendotelnih ćelija u srcu. Endotelin-1 ima pozitivno hronotropno i inotropno dejstvo. Administracija ET-1 uzrokuje koronarnu vazokonstrikciju, dovodi do ishemije miokarda i letalne ventrikularne aritmije. U akutnom infarktu miokarda ET-1 povećava miokardnu nekrozu i aritmije ali ima povoljan efekat na oporavak srca nakon infarkta u početnoj fazi remodelovanja srca. ET-1 preokreće acidozom indukovan negativan inotropan i luzitropan efekat, bez povećanja intracelularnog kalcijuma. Endotelin može da se suprotstavi aritmogenim efektima kateholamina. Tako, male koncentracije endotelina imaju protektivni efekat na srce. Osnovne indikacije za primenu antagonista endotelina jesu srčana insuficijencija, plućna hipertenzija i rezistentna arterijska hipertenzija. Dobro i pažljivo dizajnirane kliničke studije su potrebne za verifikaciju terapeutskih potencijala novih klasa lekova u kardiovaskularnoj medicini.

Nowdays, reaction time is most often used in data processing as a quantitative method and technique for information step and speed processing. The aim of this investigation was to examine everyday work pressure on reaction time nd among students. An examination included 30 students of 2 year of Medicine Faculty 15 males and 15 females. Audible and visual simple reaction time as well as choice reaction time for 2, 4 and 6 stimuli was used for reaction time measurement. Measurements were done three times a day. Achieved results acknowledge statistically significant improvement of reaction time at noon compared to reaction time in the morning in all samples except for visual simple reaction time for male students. For all kinds of stimuli, reaction time were significantly prolonged in the evening in both groups. Therefore, we have concluded that morning activities had positive impact on students functional condition but afternoon activities acted like an additional stress that altered students latent fatigue to clearly observable acute fatigue.

Systematic and programmed physical exercise, called training, play a significant role in human health and ability improvement. A moderate physical exercise is considered as a very efficient method of increasing general physical ability and reaching the top results in sport, and simultaneously contributes to health quality of persons having sedentary professions. In active sportspersons, ability of cardiovascular, respiratory and bone-muscle systems are determined by training quality itself. Sportspersons show characteristically better adaptability of neurohumoral system to effort, as well as a higher activity of intracellular enzyme systems. Well-dosed physical exercise has an exceptional influence on human health, above all by regulating cholesterol blood level and electrolyte level of serum, whose minimal change can directly affect human health. This study was aimed to establish quantity and quality of organism response to physical exercise, in regard to level of daily training, by determining lipid fractions level in serum and electrolyte composition of serum. The study involved 50 healthy men in age between 20 and 25, divided into two groups. The first group was composed by physically untrained men, chosen by the random sample method. The other group of subjects was composed by 35 active sportsmen, chosen by direct selection for the best-trained ones among them. In order to reach a submaximal exertion, we used Astrand's test of submaximal exertion on the bicycle-ergometer. Blood samples were taken immediately before and after testing. The following parameters were determined in blood serum: high-density lipoproteins (HDL), low-density lipoproteins (LDL), triglyceride + + 2+ 2+ - content, as well as concentration of sodium (Na ), potassium (K ), calcium (Ca ), magnesium (Mg ) and chlorine (Cl) ions. On the base of our research we concluded that physical exercise of submaximal intensity did not lead to any quantitative and qualitative change of lipid fractions in blood serum of untrained persons. Physically inactive persons had higher serum concentrations of triglycerides and total cholesterol in regard to the investigated sportsmen. At the same time, sportsmen showed a higher HDL content of serum. Physical exertion in sportsmen led to a significant rise of triglycerides and highdensity lipoproteins content of serum, and the levels of total cholesterol and low-density lipoproteins did not changed + ++ significantly. Physical exertion of submaximal intensity in both studied groups caused a significant increase of Na , Ca and ++ + - Mg ion concentration, while concentration of K and Cl ions did not changed significantly. Numerous clinical studies showed that moderate aerobe exercise amplifies endothelial function and reduces cardiovascular risk

Glucagon is polypeptide hormone derived from pancreas which in addition to its metabolic actions has also certain cardiovascular stimulatory effects. We've explored the effects of glucagon on hemodynamic variables (mean arterial pressure, heart rate and central venous pressure) and on catecholamine level and the electrolite level in the kanine sera. It was estimated that glucagon expressed the positive chronotropic effect and significantly lowers the central venous pressure while inconsiderably inceases mean arterial blood pressure. It also leads to transient (short-lasting) hipokaliemia and nonsignificant hipocalcemia. As the result of the action of the glucagone, the serum adrenaline concentrations were significantly increased while the serum noradrenaline concentratios were significantly decreased

It is known that the intoxication with heavy metals and pesticides is most often unmedical poisoning. In contrast to other heavy metals, for example: mercury, lead, cadmium and zinc, toxic copper activity and the mechanism of its effect are not known enough and they are not yet explained. Because of that, the aim of this work was ( with acute dog intoxication with copper sulfate ) to contribute to better clearing of biochemical mechanism as a result of copper toxical effect and to make analysis of its tissue distribution. Researching was done on adult dogs, both sexes, different races and body mass of 14- 20 kg, who were given a 10% water solution of copper sulfate in the dosage of 33mg/b.m. divided into 5 equal doses. The analysis of biochemical blood structure took the following things: total proteins, albumins, globulins, total lipids, chole2+ sterol, glucoze, transaminase (AST,ALT), catalase, peroxidase, vitamin C, proteine SH, the contretation of Cu in the serum 2+ and the content of Cu in the tissues. The results are presented in the charts and graphic presentation. All these changes can be the important directions in an biological monitoring as a biochemical indication of copper pollution in the surroundings.

Scientific research of effects of glucagon on the cardiovascular system have shown that glucagon has some
cardiostimulatory potential. The very interesting fact is that glucagon shows its cardiostimulatory effects by activating its
own, higly specific glucagonic receptors. That is way we wanted to research not only the effects of glucagon on the C.V.S.
but also its effects during the depression of the C.V.S. with high dosses of beta blocators (presolol) expecting a good
hemodinamic response. The experiment has been performed on two groups of 6 dogs. The first group of animal was treated
with i.v. bolus injections of glucagon and other group with presolol (15 mg/kg b.w.) i.v., and after that with i.v. bolus
injection of glucagon. Hemodinamic variables (mean arterial pressure, central venal pressure and hearth frequency) were
registred at the 1-st, 2-nd, 3-rd, 10-th, 20-th, 30-th and 40-th minute. The hearth frequency was registred by continous
monitoring, mean arterial pressure was registred with cateter in the arterial femoralis, while the central venal pressure was
registred over central venal cateter in v. femoralis. After the i.v. bolus injection glukagon shows higly positive effects,
followed by short-term increase of the mean arterial pressure, while the c.v.p. considerably falls. During the administration
of presolol the hearth frequency and mean arterial pressure fall considerably and progressively, while the c.v.p. rises
considerably. Glucagon, in conditions of c.v.s. depresion by high doses of presolol (15 mg /kg b.w.) considerably increases
hearth frequency and mean arterial pressure, while the c.v.p. falls considerably.