Functioning of the Human Heart in the Pron-Position.

Aim      To study intracardiac hemodynamics in healthy men in supine and prone positions.Material and methods  This echocardiography study included 14 apparently healthy men at a mean age of 38 years.Results In a prone position, the heart configuration and location in the chest changed, the heart rate increased by 7.3 %, and the transaortic flow velocity decreased by 13.7 %. Also, early and late right ventricular diastolic filling velocities and the pulmonary artery flow velocity were increased by 31.7, 11.4, and 5.6 %, respectively. In the intact tricuspid valve, the velocity and regurgitation pressure gradient were reduced by 7 % and 14.2 %, respectively.Conclusion      In a prone position, spatial changes in the location of the heart and its structures influence velocities of intracardiac blood flow, which may initiate the development of heart failure if the prone position is long-lasting.

[The influence of ecdysteroid fraction from Serratula coronata on transmembrane ionic currents of snail neurons].

Changes of the transmembrane potassium, calcium, and sodium ion currents in isolated neurons of Lymnaea stagnalis snail under the action of ecdysteroid fraction (serpisten) from Serratula coronata L. applied from outside in 0.01 -1000 microg/ml concentrations have been studied using the voltage-clamp technique. It is established for the first time that serpisten non-selectively activates the potassium and calcium ion currents (the currents amplitude increases by 2 - 15%) and reduces nonspecific membrane leakage currents in the entire range of concentrations. The sodium ion current also increased by 4 - 7% under the action of Serpisten in low concentrations (0.01 -10 microg/ml) in comparison with control, but this current decreased by 5 -10% at serpisten concentrations of 100 and 1000 microg/ml. The effects were reversible. The kinetics of currents was not changed under the action of serpisten.

Activating effect of Tanacetum vulgare L. pectin polysaccharide on ionic channels of neuronal membrane.

The membranotropic effects of TVF tanacetan pectin polysaccharide derived from Tanacetum vulgare L. was studied by the voltage-clamp method on isolated neurons of Lymnaea stagnalis mollusk. TVF in concentrations of 0.1-10.0 microg/ml nonselectively activated the outward potassium and total inward (sodium and calcium) ionic currents (slightly dose-dependently and reversibly increased their amplitude by 5-10%) and decreased nonspecific leakage current.

[Electrophysiological characteristics of the pacemaker in the atrioventricular junction of the frog heart]. / Elektrofiziologicheskaia kharakteristika peismeikera v predserdno-zheludochkovom soedinenii serdtsa liagushki.

Functional topography of the pacemaker was studied in isolated atrioventricular area of the frog heart by method of microelectrode mapping of the action patentiols. The pacemaker's quantitative characteristic is presented for the first time.

[The functional specificity of the cardiac pacemaker system]. / Funktsional'naia spetsifichnost' peismekernoi sistemy serdtsa.

On the basis of the own and literature data the original conception on pacemaker system of the heart experimentally is grounded. The new classification of the specialized structure--functional formations in the heart is suggested. The functional specificity of pacemaker system is considered in the comparative-ontogenetic aspect.

[Structure of the right muscle atrioventricular valve in the avian heart]. / Stroenie pravogo myshechnogo predserdno-zheludochkovogo klapana v serdtse ptits.

A morphometrical investigation of the right muscle atrioventricular valve in the hearts of 12 adult pigeons and 16 mature hens has been carried out. Qualitative description and designations of separate parts are given. Basing on the results obtained and on the literature data, a hypothesis is advanced that the special construction of the muscle valve, together with the main morpho-functional purpose--closing of the atrioventricular ostium during ventricular contraction--is used also to increase the internal surface of the right ventricle, increasing dimensions of the free wall (the valve is its part) and correspondingly, its contractile ability.

[Activation of the right atrioventricular valve in the avian heart]. / Aktivatsiia pravogo predserdno-zheludochkovogo klapana v serdtse ptits.

Using intramural needle electrode, in situ determinations have been made of the moment of activation of the right muscular atrioventricular valve during electrical systole of the heart. In the hen, Gallus domesticus, the electrical activation of the valve was observed 8.8 +/- 1.4 ms (mean QRS duration 25 ms) whereas in the pigeon Columba livia--5 +/- 1 ms (QRS duration 17 ms) after the beginning of ventricular depolarization, i.e. during excitation of the main bulk of the myocardium of the free wall of the right ventricle.

[Electrophysiologic characteristics of cells of the conducting system in the right atrioventricular valve of the pigeon heart]. / Elektrofiziologicheskaia kharakteristika kletok provodiashchei sistemy v pravom predserdno-zheludochkovom klapane serdtsa golubia.

Distribution of the APs of Purkinje and pacemaker cells on the atrial and ventricular surfaces of the isolated muscle of the right atrioventricular valve was studied in the pigeon heart. The presence of a constant pacemaker area was found at the atrial side of the valve throughout the extent of its base. Due to the presence of the muscle valve in the right atrioventricular orifice in the bird heart, the "extension" of the pacemaker area of the atrioventricular node and a respective obvious branching of the Purkinje fibers of the atrioventricular bundle seem to take place.