[Radioprotective properties of isothiourea derivatives with NO-inhibitory mechanism of action].

The study of the radioprotective activity of S-[2-alkyl (aryl) sulfonyl]-S-ethyl derivatives of (vinyl)-isothiourea in (he model of the survival of mice exposed to gamma-radiation at a dose of 10 Gy has shown that the incorporation of additional sulfur-containing groups does not increase the radioprotective properties of compounds. In contrast to aminoalkil thiols, the effectiveness of the radiation protection action of the isothiourea (ITU) derivatives studied clearly correlates with the NO-inhibitory activity. This fact allowed us to assume that the radioprotective effect of S-substituted ITU caused inhibition of the endogenous synthesis of NO, which promotes the development of circulatory hypoxia, and that a further search for the radioprotective agents in this class of chemicals should be considered as the search for effective inhibitors of NO-synthase (NOS).

[Effect of increased mechanical loading on the relation between the contraction of isolated cardiac muscle and the concentration of Ca++ in the perfusate].

The distension of isolated papillary muscles working isotonically or a transition to isometric working entailed an increased sensitivity of the contractile velocity to changes in perfusate Ca++ concentration. After sudden fall in Ca++ concentration, a more rapid decline of the contractile velocity in isometric mode was observed as compared to isotonic mode of working. The similar difference was found in experiments on isolated guinea pig heart working in isovolumic or auxotonic modes, though the rate of Ca++ loss by the heart was the same.

[Protective effect of extracellular K+ in the myocardium in disorders of energy metabolism].

In an experimental study on isolated isovolumetric guinea-pig hearts, a 2.2-fold reduction of the coronary duct combined with metabolic block caused by dinitrophenol (0.05 mM) resulted in an eleven-fold drop in the attained pressure, and a shorter electric systole, a smaller P wave, and an ST displacement on the ECG.

[Fast and highly-sensitive method of quantitative determination of carnosine and anserine in animal tissues].

A method is described for separation of carnosine and anserine and of the amino acids constituting them by means of thin-layer chromatography. For quantitative estimation the amino acids and dipeptides were treated with 7-chlorine-4-nitrobenzeno-2-hydroxy-1,3-diazol (NBD-chloride) and subsequently separated by chromatography on silica gel and estimated by absorption at 456-470 nm. Systems of solvents were developed for separation of both free and chemically modified amino acids and dipeptides; optimal conditions were chosen for preparation of tissue extracts and their treatment with NBD-chloride.