[The transient nature of myocardial ischemia during partial occlusion of the coronary artery in waking immobilized rabbits].

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.

[Effect of kavinton on systemic and regional hemodynamics in waking and anesthetized rats].

The effect of cavinton (vinpocetine) on the systemic and regional hemodynamic parameters was studied by the radioactive microsphere technique in experiments on conscious and anesthetized rats. Intravenous administration of cavinton (10 mg/kg) was followed by the development of hypotension and bradycardia in conscious and anesthetized animals. Administration of cavinton to anesthetized rats increased the blood flow both in the brain and in most internal organs.

[Increased natriuresis in narcotized and waking rats with spontaneous hypertension].

The influence of acute volume-salt loading on renal excretory function and hemodynamics was studied in urethane-anesthetized and conscious immobilized, spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats on osmotic diuresis. The SHR have been shown to response to the intravenous sodium chloride load with exaggerated natriuresis as compared with the WKY group. The increase in natriuresis in the SHR did not depend on diuresis changes but was due to the increased urinary sodium concentration.

[The hemodynamic and neurohumoral reactions induced by submaximal dynamic and isometric loading in hypertension patients].

Changes in systemic hemodynamics and plasma catecholamine levels during and 4 min after the end of bicycle and isometric leg exercise were studied in 12 hypertensive patients. Dynamic exercise increased heart rate more and blood pressure less than isometric exercise; plasma norepinephrine (NE) level rose by 109%. Isometric exercise increased NE level only by 18%, but maximal changes (46%) occurred during recovery, probably reflecting a washout of NE from active muscles after the end of isometric contractions.

[Measurement of cardiac output in waking rats using a Doppler ultrasonic technic].

The ultrasound Doppler technique was used for the determination of cardiac output in conscious Wistar rats. The cuff probes were placed on the ascending aorta and calibrated with the radioactive microsphere technique. The results of experiments show that Doppler ultrasound technique determines the cardiac output with high linearity.

[The development of heart failure during transvalvular catheterization of the left ventricle in spontaneously hypertensive rats].

Systemic hemodynamic parameters in 5-month-old and 10-month-old normotensive Wistar-Kyoto and spontaneously hypertensive (SHR) conscious rats were studied with microsphere technique. Cardiac index was similar in both strains of rats and was not significantly different between 5 and 10 months. Left ventricle catheter implantation through the right common carotid artery evoked the development of heart failure in 10-month-old SHR (in the first day after operation).

[Hemodynamics in waking rats undergoing testicular exposure to elevated temperature].

Changes of systemic and regional hemodynamic parameters of the rat during heating of the lower part of the body in 41 degrees C water and after removing of the testis from abdominal cavity, were measured with labeled microsphere technique. Experimental cryptorchism reduced the blood pressure due to a decrease in total peripheral resistance. Hyperthermia of the testis increased the heart rate.

Considerations in use of microspheres for myocardial blood-flow measurements in long-term experiments on rats.

The loss of 15-micron radioactive microspheres from rat myocardium was determined in long-term experiments. Heterotopic heart transplantation was used for the evaluation of microsphere losses. Microspheres were injected into the left ventricle of a donor rat, and the number of microspheres entrapped in the heart was measured after its isolation.

[The pharmacology of endothelium-dependent vascular reactions].

The review deals with the critical analysis of the recent publications showing an important role of the endothelium in the mechanism of vasodilation caused by endogenous agents (acetylcholine, bradykinin, substance P, ATP, histamine, thrombin) and pharmacological agents (clonidine, hydralazine, mellitin, calcium ionophore A 23187). The mechanism of the endothelium-dependent vasodilatation is based on the release of the endothelium-derived relaxant factor (EDRF). In 1987-1988 it was shown that in some cases EDRF is NO.

[Effect of opioid peptides on regional hemodynamics in waking rats].

The hemodynamic effects of intravenously administered relatively selective mu-(DAGO) and delta-(DADL) opioid agonists were investigated in conscious rats. The radioactive microsphere technique was used to measure regional blood flow in 10 zones before and 5 min after bolus injection of each peptide. Both opioid agonists in a dose of 1 mumol/kg produced transient hypotension, bradycardia and apnoea.

[Analysis of the baroreflex activation of the sympathetic system in waking cats induced by urapidil and sodium nitroprusside].

The responses of the sympathetic system to a stepwise decrease of arterial blood pressure by administering sodium nitroprusside or urapidil were studied in experiments on conscious cats with preliminarily implanted transducers and catheters. Adrenaline and noradrenaline concentrations in arterial and venous blood plasma were measured by means of a high performance liquid chromatography. It was shown that when nitroprusside was used for lowering blood pressure there occurred reflex activation of the sympathetic system.

[Mechanism of the effect of atriopeptin on regional blood flow].

Atriopeptin exerts a direct regulatory vasodilating effect on the mechanism of the regional blood flow maintenance. Under preliminary activation of vascular tone the atrial factor can produce the smooth muscle relaxation. Atriopeptin II is the most active among the three types of atriopeptin, atriopeptin III is the least active.

[A method for inducing the point C----T transitions in DNA sequences corresponding to the ends of restriction sites].

A new method for inducing of C----T substitutions into cytosine-containing restriction sites is developed. The method, based on the selective modification of cytosine residues in DNA sticky ends by sodium bisulfite, was illustrated by induction of a base substitution (C----T at the BamHI site of pBR322 plasmid DNA.

[Effects of opioid peptides on rats with a second heart transplanted into the abdominal cavity].

To determine whether opioid peptides have direct effects on myocardium we compared the effects of enkephalin analogs DAGO and DADL on both an innervated heart and a denervated heterotopically transplanted heart in the same animal. DAGO and DADL injected intravenously into anesthetized rats with two hearts produced hypotension, fall in end-systolic left ventricular pressure of both recipient's and donor's heart, bradycardia and decreasing of contractility in recipient's heart. Opioid peptides exerted no chronotropic effect and a slight positive inotropic effect on denervated transplanted heart.

[2-Deoxyglucose as a tool for analyzing the humoral component of the cardiovascular reaction to stress].

Blood pressure (BP), heart rate (HR), adrenaline (A) and noradrenaline (NA) effects of 2-desoxyglucose (500 mg/kg i.v.) were studied in conscious chronically instrumented wistar rats.

[Hypotensive activity of dinitrosyl complexes of iron and proteins in anesthetized animals].

It had been shown before that dinitrosyl iron complexes (DNIC) administration led to long-lasting decrease in animal arterial pressure. It was suggested that this effect depended on protein DNIC formation which were an NO-store in animal tissues. NO was hypotensive agent.

2-Deoxy-D-glucose-induced central glycopenia differentially influences renal and adrenal nerve activity in awake SHR rats.

2-deoxy-D-glucose (2-DG) evokes an increase in the efferent discharge rate of the adrenal nerve in narcotized rats and rabbits. The study reported here was undertaken to determine the sympathetic nerves and blood pressure responses to i.v.

[Hypotensive effect of dinitrosyl iron complexes in experiments on waking animals].

Changes in arterial pressure evoked by dinitrosyl iron complexes (DNIC) were studied in conscious normotensive (Wistar) and spontaneously hypertensive (SHR) rats. Doses from 1 to 10 mcM/kg of DNIC evoked dose-dependent decrease in blood pressure for two hours. SHR rats were more sensitive to the effect of the drug than normotensive Wistar rats.

Effect of a prostacyclin derivative (iloprost) on regional blood flow, sympathetic nerve activity, and baroreceptor reflex in the conscious rat.

We have investigated the hemodynamic actions of iloprost, a stable prostacyclin derivative, in conscious, chronically instrumented rats. Given intravenously by 10-min infusions at doses ranging from 0.0375 to 4 micrograms/min, iloprost lowered mean arterial blood pressure in a dose-dependent and reversible fashion.

[Blood flow in skin wound tissue and systemic hemodynamics as affected by a collagen-dalargin complex].

In has been demonstrated that a collagen-dalargin complex increases blood flow in the granulation tissue (microsphere technique) due to the formation of new capillaries and a decrease in the vascular resistance. Dalargin had no effect on the capillary blood flow in the unaffected tissues. It has been concluded that the wound healing effect of dalargin may be related to its involvement in angiogenesis regulation.