Antioxidants as antiarrhythmic drugs.

Experiments on rats and rabbits using models of arrhythmias induced by vasopressin, epinephrine, strophanthin, and CaCl2 showed that antioxidants derived from 1,4-dihydropyridines, dibunol, and alpha-tocopherol possessed antiarrhythmic effects. Administration of these antioxidants decreased the occurrence of extrasystoles, disturbances of atrioventricular conductivity and ventricular fibrillation. These drugs also prevented changes in membrane phospholipid composition, inhibited activation of peroxidation, decreased phospholipase activity, prevented a decrease of Ca2+ ATPase and Ca2+ binding and uptake by sarcoplasmic reticulum, and increased sarcolemmal Na+, K+-ATPase, sarcoplasmic reticulum creatine phosphokinase.

[Anti-arrhythmic action of preparations of the dihydropyridine series]. / Antiaritmicheskoe deistvie nekotorykh preparatov digidropiridinovogo riada.

The derivatives of the dihydropyridine series, sodium salt of 2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydronicotinic acid (drug I) and disodium salt of 2,6-dimethyl-1,4-dihydropyridine-3,6-bis-carbonyloxyacetic acid (drug II), reduce or completely prevent (depending on the dose) arrhythmias of different types (disturbances of atrioventricular conduction, extrasystoles, heart fibrillation) induced by vasopressin, calcium chloride and strophantine. Study of the lipid composition and activity of lipid-dependent enzymes of sarcoplasmic reticulum membranes has demonstrated that the antiarrhythmic effect of the drugs under study is linked with their antioxidant action favouring the preservation of enzymes involved in Ca2+ transport.

Vasopressin and cardiovascular system in aging.

The studies concerned age-dependent peculiarities of the vasopressin effect on the hemodynamics and tone of the coronary vessels in dogs, the contraction of the isolated vascular strip in rats, and the hemodynamic and ECG indices in rabbits and in rats. The data obtained indicate the great sensitivity of old vessels to vasopressin. In aging, both humans and animals show a rise of vasopressin concentration in the blood. Age-dependent differences of the vasopressin effect on the kallikrein-kinin system, adenosine metabolism, the contents of prostaglandins and cyclic AMP have been established. High sensitivity to vasopressin in combination with its increased concentration in the blood is an important factor that contributes to the development of arterial hypertension and ischemic heart disease.

[Blood vasopressin and the kallikrein-kinin system in chronic ischemic heart disease]. / Vazopressin i kallikrein-kininovaia sistema krovi u bol'nykh khronicheskoi ishemicheskoi bolezn'iu serdtsa.

The blood vasopressin content and kinin system activity were studied in 83 patients with chronic ischemic heart disease of various severity. It was established that the blood vasopressin concentration increases with an increase in the severity of the disease. A high degree of correlation between changes in vasopressin content and in components of the kinin system was revealed: increase in the concentration of vasopressin is attended by activation of the kallikrein-kinin system. The mechanisms of the interrelationship of the vasopressin and kinin content are discussed. It is suggested that vasopressin may play a role in the pathogenesis of chronic ischemic heart disease.

[Blood vasopressin concentration is patients of different ages with hypertension]. / Kontsentratsiia vazopressina v krovi u liudei raznogo vozrasta pri gipertonicheskoi bolezni.

The concentration of blood vasopressin was investigated in apparently healthy persons and in patients with I--II degree hypertension, aged from 20 to 80 years. Vasopressin concentration was determined by the biological method according to the antidiuretic effect of ethanol-anesthetized and constantly hydrated rats on an original 5-channel apparatus. The results obtained showed the blood vasopressin concentration to increase with age. In patients with the I--II degree hypertensive disease the mentioned concentration was significantly higher than in healthy persons of the same age. Close correlation coefficient was revealed between the blood vasopressin concentration and minimal arterial blood pressure values.

[Hormonal regulation of the heart in aging]. / Gormonal'naia reguliatsiia serdtsa pri starenii.

It was established in experiments on adult (8--12 month) and old (26--32 month) rats that in ageing the sensitivity of the cardiovascular system to certain hormones--adrenaline, vasopressin, insulin, thyroxine, estradiol dipropionate--grows while its reactivity to them diminishes. The administration of these hormones causes significant changes in hemodynamics and myocardial contractility. Adrenaline and thyroxine lead to an increase in the blood minute and stroke volume, arterial pressure, cardiac index and left ventricular work index, maximum rate of intraventricular pressure growth, maximum rate of myocardial fiber shortening, and in the contrastility index. Vasopressin and insulin cause a decrease in the indices of general hemodynamics. The increased sensitivity of the heart to hormones at old age and diminution of its reactivity lead to prolonged, protracted reactions of the cardiovascular system in elderly and old individuals.

E1Age and the development of coronary insufficiency under the influence of vasopressin. / Vozrastnye osobennosti razvitiia koronarnoi nedostatochnosti pod vliianiem vazopressina

Experimental results showed that the ECG changes (elevation of T wave, a shift of the S-T segment and disturbances of the atrio-ventricular conduction) under the effect of vasopressin occurred in rats aged 24-26 months after lower doses of vasopressin than in the animals aged 10-12 months. With the administration of the same doses coronary insufficiency was more pronounced in the old animals (more frequent disturbances of the atrio-ventricular conduction, grade II or III, and greater derangement of general hemodynamics).

[Vasopressin concentration in the blood and sensitivity of the cardiovascular system to it during aging]. / Soderzhanie vazopressina v krovi i chuvstvitel'nost' k nemu serdechno-sosudistoi sistemy pri starenii

With aging the content of the blood vasopressin increases. In old animals smaller doses of vasopressin induce coronary insufficiency (rise of T wave, shift of S-T segment, disorders of the atrio-ventricular conductivity). On continuous administration of vasopressin (during a month), arterial hypertension appears only in old animals due to increase in cardiac output, stroke volume at unchanged cardiac rhythm, and to some decrease in the total peripheral resistance.