Two types of electrogenic alterations of cardiac cell membranes during vulnerability are shown. The first one: selective activation only of slow response close to the source of miocardium stimulation and a simultaneous appearance of an extrasystolic impulse of great latency (100 ms and more) far from the source of stimulation. Extrasystolic latency is considered as the time of slow response propagation. Slow propagation is due to the small size of reentry during vulnerability. The second one: selective activation only of fast Na channels leads to generation of a very short response (10-20 ms duration)--cardiac spike. Appearance of such a spike is also favourable for reentry during vulnerability.

Action Potentials↗

PubMedDate not supplied

[Effect of falloidin on permeability of intercellular channels for inorganic ions and fluorescein].

It has been shown on larva gland that falloidin - a toxic of toadstool inducing an increased number of membrane microfilaments-affects the efficiency of intercellular transfer of small inorganic ions and molecules of organic dye fluorescein-Na. The data obtained are in favour of the participation of microfilaments in the regulation of intercellular diffusion communication.

Animals↗

PubMedDate not supplied

[Redistribution of Ca2+ ions in lymphocyte suspensions after treatment with an ionophore].

Ionophore A23187 induces three-phase kinetics of reduction of chlorotetracycline (CTC) lauded lymphocyte fluorescence: fast reduction, low increase and lower reduction of fluorescence. We suggested the following explanation of kinetics. The first phase is extinguishing of the Ca2+ - CTC complex fluorescence induced by ionophore A23187 perturbation of the cell membrane, the second one is the energy dependent Ca2+ entry into the cell and the third one is the slow efflux of Ca2+ ions from the cell to concentration gradient.

Animals↗