Temporary cardiointerval organization with varying degrees of acute normobaric hypoxia in a healthy person

The influence of acute normobaric hypoxia (ANH) on the male heart chronotropic effects was studied. Thus, a mild degree of ANH (14.5 % O2, 20 min), causing a decrease in blood oxygenation by 6.3 abs. %, accompanied by an initial (by 5 min) decrease in the RR and QT intervals. The average degree of ANH (12.3% O2) leads to a decrease in blood oxygenation by 19.7 abs. %. At the same time, in inverse relationship to the developing hypoxemia, RR and QT significantly decrease. Corrected values (Pc, PQc, QRSc, QTc) increase during the action period of an average degree of hypoxia, indicating an increase in the proportion of atrial contraction time, atrioventricular conduction of excitation and electrical ventricular systole in the total RR duration, which, apparently, provides optimal systolic heart effect. Key words: human, hypoxia, blood oxygenation, cardiointervals.

Spatio-temporal analysis the results of solving the inverse problem of electrocardiography

The results of the development and testing an algorithm for the physiological interpretation the results of solving the inverse problem of electrocardiography are presented. The solution to the inverse problem of electrocardiography is the distributions of equivalent current sources on the quasi-epicardium, restored from the electric potentials created by the heart on the surface of the chest. The developed algorithms are based on the space-time analysis of the distributions of equivalent current sources on the quasi-epicardium. The development and testing of the algorithm was carried out using a simulation model of the electrical activity of the heart based on cellular automata. The efficiency of the algorithm has been demonstrated when simulating the electrical activity of the heart in normal conditions, as well as in the presence of pathological changes in the myocardium in the form of areas with delayed conduction of excitation.

Steinach. Ueber die centripetale Erregungsleitung im Bereiche des Spinalganglions. (On the centripetal conduction of excitation along the dorsal nodes). - Arch of Pfluger. Bd. 78, p. 291

According to the generally accepted view, sensory excitation in the spinal nerve system reaches the spinal cord through the nerve cells of the dorsal nodes, which from this point of view with full right can be attributed to the category of sensitive nerve cells. Working in the early 90s on the issue of negative fluctuations, Steinach came across a fact that remained completely inexplicable for him until the last day.

Electrhopysiological Effect of the Polyamine Spermine in Normoxic and Ischemic Ventricular Myocardium

Cytoplasmic polyamines (PA) are involved in control of many cellular functions and are well known as regulators of so called inward-rectifier potassium ion channels. Nevertheless, functional significance of extracellular PA in the heart is poorly elucidated. Aim of this study was to study effects of endogenous PA spermine in the ventricular myocardium. Effects of the extracellular spermine were investigated in isolated multicellular preparations of rabbit and rat ventricular myocardium. Langendorff-perfused isolated rat and rabbit hearts were also used. Action potential (APs) duration and pattern of excitation in ventricular myocardium were estimated using standard microelectrode technique and optical mapping. Functional refractory periods were assessed in Langendorff perfused hearts with the help of programmedelectrical stimulation of the ventricle. In this study extracellular PA spermine (0.1–5 mM) induced shortening of the APs in multicellular preparations of rat ventricular myocardium registered using sharp microelectrode technique. However, spermine caused only weak effect in preparations of ventricular myocardium from rabbit heart: highest tested concentration of spermine (5 mM) induced 4.7 % APs shortening. Similarly, 0.1–1 mM of spermine was unable to alter substantially ventricular effective refractory periods in isolated perfused rabbit hearts. In two animal species tested (rat and rabbit) 0.1–1 mM of spermine failed to affect conduction velocity and activation pattern in ventricles of isolated Langendorff-perfused hearts under normoxia. However, in the rat no-flow model of ischemia-reperfusion extracellular spermine improved conduction of excitation in ventricles. Our results allow suggesting that extracellular spermine can prevent ischemia-induced proarrhythmic changes in ventricular myocardium probably due to reduction of calcium accumulation, but this effect is significant only when PA is applied in millimolar concentrations. Also, potential anti-ischemic effect of the PA may be species specific.

Conduction and coordination in deganglionated ascidians

The behaviour of Chelyosoma productum and Corella inflata (Ascidiacea) was studied in normal and deganglionated animals. Chelyosoma productum lived for over a year after deganglionation and the ganglion did not regenerate. Electrophysiological recordings were made from semi-intact preparations. Responses to stimulation and spontaneous activity continued to be transmitted through the body wall and branchial sac after deganglionation. Spread was slow, decremental, and facilitative. Treatment with >10 µg·mL-1 d-tubocurarine abolished all responses, indicating that nerves mediate conduction of excitation after deganglionation. Histological study using cholinesterase histochemistry and immunolabelling with antisera against tubulin and gonadotropin-releasing hormone showed no evidence of a peri pheral nerve net in regions showing conduction, contrary to previous claims. The cell bodies of the motor neurones were found to lie entirely within the ganglion or its major roots. Their terminal branches intermingled to form netlike arrays. Sensory neurons were identified with cell bodies in the periphery, in both the body wall and the branchial sac. Their processes also intermingled in netlike arrays before entering nerves going to the ganglion. It is concluded that the "residual" innervation that survives deganglionation is composed of either interconnected motor nerve terminals, interconnected sensory neurites, or some combination of the two. In re-inventing the nerve net, ascidians show convergent evolution with sea anemones, possibly as an adaptation to a sessile existence.