[The anti-anginal effect of diltiazem in patients with stable exercise-induced stenocardia and vasospastic stenocardia compared with the effect of nifedipine]. / Antianginal'nyi éffekt diltiazema u bol'nykh so stabil'noi stenokardiei napriazheniia i vazospasticheskoi stenokardiei v sravnenii s vliianiem nifedipina.

Paired bicycle ergometric tests were performed in 13 patients with stable exercise-induced angina who took a single dose of diltiazem (120 mg) and nifedipine (30 mg). Four patients with vasospastic angina underwent repeat ergometrine tests along with the both drugs given in the same doses. The two drugs significantly increased exercise tolerance: exercise time was increased by 83% with diltiazem and by 41.9% with nifedipine, its capacity was elevated by 78.9 and 30.2%, respectively, the "double product" at the peak of exercise was raised by 17.0 and 18.7%, respectively). With intravenous injection of ergometrine, diltiazem and nifedipine eliminated or delayed the spastic reaction of coronary arteries in most cases.

[The transient nature of myocardial ischemia during partial occlusion of the coronary artery in waking immobilized rabbits]. / Tranzitornyi kharakter ishemii miokarda pri chastichnoi okkliuzii koronarnoi arterii u bodrstvuiushchikh immobilizovannykh krolikov.

The radioactive microsphere technique was used to study mechanisms of disappearance of myocardial ischemia during partial occlusion of the left descending anterior coronary artery with implanted device in conscious immobilized rabbits. Microspheres (15 microns, NEN, USA) were injected before occlusion, immediately after ST-segment elevation and after disappearance of ST-segment shift. In ischemic region blood flow dropped by 45% (p less than 0.05) and mean blood pressure decreased by 12% (P less than 0.05) on the 1st minute of coronary occlusion. 8-15 min later ST-segment elevation disappeared and the blood flow in ischemic region became higher than control level (on the average by 35%). It is suggested that ischemia is abolished mainly by dilatation of distal coronary vessels, than by activation of collateral blood flow.

[Changes in systemic and regional hemodynamics in the acute period of myocardial infarction in conscious rabbits]. / Izmeneniia sistemnoi i regionarnoi gemodynamiki v ostrom periode infarkta miokarda u bodrstvuiushchikh krolikov.

Systemic and regional hemodynamics (radioactive microspheres of 15 mcm) were studied in 7 conscious immobilized rabbits 30 min, 24 and 72 hours after left coronary artery occlusion (group 1) and 30 min and 24 hours after the occlusion in 5 rabbits who died the next day (group 2). Significant changes in myocardial blood flow, white cerebral matter and kidneys were only observed 24 h after coronary artery occlusion in group 2, simultaneously with a significant (29%) decrease in cardiac output. It is suggested that significant regional blood flow changes associated with acute experimental myocardial infarction only occurred in the presence of heart failure in rabbits.

[Antifibrillatory effect of the calcium antagonist foridon in acute myocardial ischemia in conscious rabbits]. / Antifibrilliatornoe deistvie antagonista kal'tsiia foridona pri ostroi ishemii miokarda u bodrstvuiushchikh krolikov.

The effect of ryodipine on disorders of rhythm induced by occlusion of the left descending coronary artery was studied in experiments on 40 conscious immobilized rabbits. Ryodipine was injected intravenously (50 mcg/kg 5 minutes prior to and 25 mcg/kg after occlusion). Ventricular fibrillation developed in 19 (66%) rabbits of the control group and in 3 (27%) animals in the experimental group (p less than 0.03). The parameters of systemic and regional hemodynamics were studied in 7 rabbits of the control group and in 5 animals of the experimental group before and 30 minutes after occlusion; microspheres (15 mcm) labelled with various radioactive isotopes were used in the study. The blood flow in the intact myocardium of rabbits given ryodipine was higher than the initial level by 14% (p less than 0.05). The coronary fraction of the cardiac output increased by 21%. It is concluded that the antifibrillation effect of ryodipine is due to its favourable action on the myocardial blood flow.

Some mechanisms of nonspecific antiarrhythmic action of phosphocreatine in acute myocardial ischemia.

Using isotope-labeled microspheres (diameter 15 microns) it was shown that phosphocreatine at a dose of 300 mg/kg does not affect the myocardial blood flow in the ischemic zone during acute occlusion (5 min) of the left anterior descending coronary artery (LAD) in dogs. Intravenous administration of NaCl hypertonic solution which contained the same amount of Na+ as 300 mg/kg of phosphocreatinine disodium salt prevented the development of ventricular fibrillation during acute LAD occlusion in dogs. Under these conditions excitation conduction velocity significantly increased. Experiments in isolated intraventricular rabbit septum have showed that the addition of phosphocreatine or phosphocreatinine to the perfusion medium at a concentration of 10 mmole/liter increased excitation conduction velocity in ischemic myocardium. However, when changes in perfusate Na+ and Ca2+ concentration produced by addition of phosphocreatine or phosphocreatinine were compensated, these compounds do not affect excitation conduction velocity. On the other hand, the alterations similar to those produced by the addition of phosphocreatine or phosphocreatinine led to the same increase of excitation conduction velocity. The results obtained indicate an important role of the changes of blood plasma ionic composition on intravenous administration of phosphocreatine in electrophysiological and antiarrhythmic effects of this substance during acute myocardial ischemia.

[Anti-angina effect of foridon in patients with stable exertion-induced stenocardia]. / Antianginal'nyi effekt foridona u bol'nykh so stabil'noi stenokardiei napriazheniia.

Twenty-three patients with coronary heart disease and stable angina of effort who took a single dose (30 mg) of ryodipine and nifedipine underwent exercise tests on a bicycle ergometer. Ten patients received ryodipine in two doses and placebo by a single-blind protocol. The single dise of ryodipine increased exercise time by 36% and intensity by 40%. Nifedipine produced the same action. When given in a dose of 150 mg/day for a short period of time, ryodipine reduced the frequency of anginal attacks by 39% and the number of nitroglycerin tablets used by 30%. The duration of physical exercise and its performance were increased by 53% and 63%, respectively. The effect was identical at 250 mg per day. The results proved ryodipine to be an effective antianginal agent.

[Effect of the calcium antagonists foridon and nifedipine on systemic hemodynamics and myocardial blood flow in dogs with acute myocardial ischemia]. / Vliianie antagonistov kal'tsiia foridona i nifedipina na sistemnuiu gemodinamiku i miokardial'nyi krovotok pri ostroi ishemii miokarda u sobak.

Systemic haemodynamic and myocardial blood flow effects of ryodipine and nifedipine have been studied during acute transitory coronary occlusion in the open-chest anesthetized dogs. Acute ischemia has been done by occlusion of left anterior descending coronary artery for 5 min. Cardiac output and blood flows in the ischemic, lateral border and intact areas of the myocardium were defined with 15 mcm plastic radiolabelled microspheres. Drugs were administered intravenously in equihypotensive doses. Both drugs prevented fall of cardiac index during occlusion, decreased arterial pressure and total peripheral resistance but heart rate remained unchanged. Ryodipine as well as nifedipine considerably increased blood flow (42 +/- 15% and 85 +/- 23%, respectively, P less than 0.05) in the intact zones of the left ventricle, but they did not affect the blood flow in the ischemic zone.

[Method of radionuclide determination of coronary blood flow: experimental verification and clinical testing]. / Metod radionuklidnogo opredeleniia koronarnogo krovotoka: éksperimental'naia proverka i klinicheskaia aprobatsiia.

For quantitative assessment of the coronary blood flow in diagnostic examination of CHD patients the authors have proposed a new method for determination of absolute values of the coronary blood flow by intragastric administration of 99m Tc-labeled human serum albumin microspheres with subsequent whole body scintigraphy and comparison of scintillation count intensity over the heart area and the whole body. The results of experiments on 13 rabbits for verification of the method and the results of clinical testing in 20 patients were presented. The proposed method was shown to ensure adequate assessment of the coronary blood flow in ml/min. the patient's safety without interfering in routine coronary angiographic investigation, providing very important additional diagnostic information. The method was recommended for clinical diagnostic practice in x-ray departments of cardiological hospitals.

[Various hemodynamic mechanisms of the hypertensive reaction in immobilization-induced stress in rabbits and rats]. / Razlichnye gemodinamicheskie mekhanizmy gipertenzivnoi reaktsii pri immobilizatsionnom stresse u krolikov i krys.

The radioactive microsphere technique was used to measure the cardiac output, regional blood flows and resistances in conscious rabbits and rats before and after 30-minute immobilization. Immobilization evoked blood pressure rise in both species. Cardiac output was reduced and total peripheral resistance increased in rabbits. Reverse changes of these parameters were observed in rats. Blood flow was reduced in the liver and the right ventricle in rabbits, and in the testes in rats. In immobilized rats, regional blood flow increased in skeletal muscles, the heart, the adrenals and the liver. These experiments demonstrate different hemodynamic mechanisms of immobilization-induced hypertension in rabbits and rats.

[Hemodynamic mechanisms of the hypotensive action of the new calcium antagonist foridon in acute hypertension in rabbits. A comparison with nifedipine]. / Gemodinamicheskie mekhanizmy gipotenzivnogo deistviia novogo antagonista kal'tsiia foridona pri ostroi gipertonii u krolikov. Sravenie s nifedipinom.

The radioactive microsphere technique was used to study hemodynamic mechanisms of action of 2 calcium antagonists--foridon and nifedipine in conscious rabbits with acute hypertension evoked by immobilization. Microspheres were injected before and 5 min after bolus i.v. injection of equihypotensive (10% blood pressure drop) doses of nifedipine (30 mcg/kg) and foridon (50 mcg/kg). Nifedipine in most cases decreased cardiac index by 7% without significant changes in regional hemodynamic. After foridon injection total peripheral resistance decreased by 19% (P less than 0.05) and cardiac index increased by 18%. There were increase in blood flow: in the heart by 34% (P less than 0.05), in the skeletal muscle by 41% (P less than 0.05) and in testes by 12% (P less than 0.05). The results show that in acute stress-induced hypertension these dihydropyridine-derivatives have different hemodynamic mechanisms of action: nifedipine preferentially depress myocardial contractility, whereas foridon dilates blood vessels.