Role of nitric oxide in the regulation of mechanosensitive ionic channels in cardiomyocytes: contribution of NO-synthases.

The role of NO in the regulation of currents passing through ion channels activated by cell stretching (mechanically gated channels, MGC), particularly through cation-selective K(+)-channels TRPC6, TREK1 (K(2P)2.1), and TREK2 (K(2P)10.1), was studied on isolated mouse, rat, and guinea pig cardiomyocytes using whole-cell patch-clamp technique.

Role of nitric oxide in activity control of mechanically gated ionic channels in cardiomyocytes: NO-donor study.

Whole-cell ionic currents through mechanically gated channels (MGC) were recorded in isolated cardiomyocytes under voltage clamp conditions. In unstrained cells, NO donors SNAP and DEA-NO activated MGC and induced MG-like currents. In contrast, in stretched cells with activated MGC, these NO-donors inactivated and inhibited MGC.

Morphological analysis of myocyte relationships in the sinoatrial node in rats.

The presence of action potentials of working atrial cardiomyocytes among action potentials of true and latent pacemakers was revealed in the part of bidimentional maps of distribution of action potentials of sinoatrial node cells on the frontal surface of the right atrium under conditions of short-term culturing using intracellular glass microelectrodes. Detailed submicroscopical analysis of the node tissue was conducted. Sinoatrial node of rat heart consists of typical nodal cells and transition-type cardiomyocytes.

[Morphophysiological organization of the sinoatrial node of the rat heart].

A combined morphophysiologic study of the rat heart sinus node pacemaker cells showed this conductive formation to comprise true and latent pacemakers. The latent pacemaker cell population is heterogeneous in terms of electric activity as well as morphology. The electrophysiologic and morphologic characteristics of latent pacemaker cells undergo a smooth change from centre to periphery of the sinus node.

[Action of noradrenaline and dopamine on the pacemaker cells of the normal rat sinus node and in pharmacological sympathectomy].

The authors studied the action of the physiological concentrations of catecholamines on the major parameters of the action potentials of the true pacemakers, using a graphic analysis of their electric activity at the intracellular microelectrode lead. Desympathization was carried out with the help of daily intraperitoneal injections of guanethidine solution for six weeks. Noradrenaline and dopamine have a similar effect on the electrogenesis of the pacemakers by decreasing a relative threshold of auto-stimulation and decreasing the steepness of the potential growth in phase 4 on the curve of the action potential.

[Ultrastructure of the pacemaker cells of the sinoatrial node in rats].

Ultrastructure of the cells generating the action potential, specific for the pacemaker of the sinuous-auricular node has been studied. The cells are labelled with lanthanum chloride by means of the registrating microelectrode. Two types of pacemakers are revealed.

[Identification of rat sinus node pacemaker cells by intracellular injection of lanthanum ions].

Action potentials of pacemaker cells were recorded on an isolated preparation of rat right atrium. Lanthanum ions were injected via a recording microelectrode. The sinus node area was treated for electron microscopy.

[Cytofluorimetric study of small, intensely fluorescing cells in the atria of rats following a single injection of guanethidine].

The fluorescence intensity of small high-fluorescent (SHF) cells of rat auricles was measured after the treatment by the modified Falk method in health and 3,14 and 72 hours after a single injection of guanethidine. No significant changes in the fluorescence intensity were found on analysis of the entire pool of SHF auricular cells and of individual SHF cells, while SHF cells of the clasters of the superior caval vein and interauricular septum manifest counterphasic deviations from the basal line of fluorescence, with these deviations being most remarkable 14 hours after the injection. The changes in the fluorescence intensity of SHF cells, which were seen within the periods of time corresponding with the minimum noradrenaline content in the heart allow the conclusion that SHF cell function is in good agreement with the heart noradrenaline level.