ABSTRACT
Inotropic effects of yttrium acetate (Y³âº) on contractions of myocardium preparations of the frog Ra- na ridibunda as well as on respiration and the inner membrane potential (Δψmito) of isolated rat heart mi- tochondria were studied. It was found that 2 mM yttrium in Ringer solution significantly reduced the am- plitude of myocardium contractions evoked by electric stimulation and increased the half-relaxation time (n = 5). In experiments with Ca²âº, Y³âº decreased Ca²âº-dependent oxygen consumption rate of rat heart mitochondria, energized by glutamate and malate, impeded the reduction in respiration of these mito- chondria in state 3 or uncoupled by 2,4-dinitrophenol, and inhibited Ca²âº-induced decrease in their inner membrane potential. These data are important to better understand the mechanisms of Y³âº effects on myocardial calcium-dependent processes. Possible mechanisms of negative inotropic effect of Y³âº on the myocardium and its influence on the Ca²âº-dependent processes in rat mitochondria are discussed.
Subject(s)
Calcium/metabolism , Membrane Potential, Mitochondrial/drug effects , Mitochondria, Heart/metabolism , Myocardium/metabolism , Myocytes, Cardiac/metabolism , Oxygen Consumption/drug effects , Yttrium/pharmacology , Animals , Male , Myocardium/cytology , Myocytes, Cardiac/cytology , Rana ridibunda , Rats , Rats, WistarABSTRACT
The inotropic effect of a new probiotic product on myocardial contractility of the frog Rana ridibunda and the effect of probiotic product on the rat cardiac mitochondria swelling were studied. In both cases, the comparison with known cardioprotector diazoxide was done. Probiotic product and diazoxide were shown to cause a dual effect on the maximum force induced by the muscle sample during spontaneous atrial contraction. Addition of agents caused a negative impact, while washing out exerted a positive inotropic effect. At the same time probiotic product has virtually no effect on the amplitude of contraction induced by electrical stimulation of the ventricle fragments. Probiotic product decreases both proton passive permeability in the inner mitochondrial membrane, and potassium active transport in mitochondria caused by activation of K(+)-uniporter of cardiomyocytes. A possible mechanism of action of probiotic product is discussed.
Subject(s)
Cardiotonic Agents/pharmacology , Diazoxide/pharmacology , Mitochondria, Heart/metabolism , Myocardial Contraction/drug effects , Probiotics/pharmacology , Vasodilator Agents/pharmacology , Animals , Biological Transport, Active/drug effects , Potassium/metabolism , Rana ridibunda , Rats , Rats, WistarABSTRACT
A variety of active agents increasing [Ca2+]i in cultivated skeletal myocytes have been investigated. It was shown that, out of the agents such as noradrenaline, carbacholine, caffeine, cyclopiazonic acid, and potassium solution, only the last caused the formation of slow calcium waves in skeletal myocytes. These waves propagated not only near the location of the cell nucleus but also along the whole length of myocytes. It is supposed that this wave process can be related to the modulation of excitation-relaxation processes in skeletal muscles.
Subject(s)
Calcium/metabolism , Muscle Fibers, Skeletal/metabolism , Animals , Animals, Newborn , Caffeine/pharmacology , Carbachol/pharmacology , Cells, Cultured , Indoles/pharmacology , Muscle Fibers, Skeletal/drug effects , Norepinephrine/pharmacology , Potassium/pharmacology , RatsSubject(s)
Calcium Signaling/drug effects , Calcium/metabolism , Muscle Fibers, Skeletal/physiology , Potassium Chloride/pharmacology , Animals , Animals, Newborn , Calcium Signaling/physiology , Cell Culture Techniques , Cells, Cultured , Culture Media , Muscle Contraction/physiology , Muscle Fibers, Skeletal/cytology , Muscle Fibers, Skeletal/metabolism , Rats , Rats, Wistar , SolutionsSubject(s)
Acetylcholine/pharmacology , Calcium/metabolism , Muscle Cells/drug effects , Muscle, Skeletal/drug effects , Norepinephrine/pharmacology , Adrenergic alpha-Agonists/pharmacology , Animals , Animals, Newborn , Calcium/pharmacology , Calcium Channel Blockers/pharmacology , Calcium Signaling/drug effects , Cells, Cultured , Chelating Agents/pharmacology , Dantrolene/pharmacology , Dose-Response Relationship, Drug , Egtazic Acid/pharmacology , Muscle Cells/cytology , Muscle Cells/metabolism , Muscle Relaxants, Central/pharmacology , Muscle, Skeletal/cytology , Muscle, Skeletal/metabolism , Nifedipine/pharmacology , Rabbits , Rats , Rats, Wistar , Time Factors , Vasodilator Agents/pharmacologySubject(s)
Cell Differentiation/drug effects , Neurites/metabolism , Probiotics/pharmacology , Animals , PC12 Cells , RatsSubject(s)
Receptors, Glutamate/physiology , Synaptic Transmission/physiology , 2-Amino-5-phosphonovalerate/pharmacology , 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology , Action Potentials , Animals , Cells, Cultured , Electric Stimulation , Excitatory Amino Acid Antagonists/pharmacology , Excitatory Postsynaptic Potentials , Hypothalamus/drug effects , Hypothalamus/physiology , Rats , Receptors, Glutamate/drug effects , Synaptic Transmission/drug effectsABSTRACT
The effect of MDI, the agent of plant origin, on the cell cycle and the number of micronuclei in human lymphocytes after gamma-irradiation has been studied. It has been found that the treatment of lymphocytes with MDI stimulates DNA synthesis and reduces the delay of irradiated cells in (G2 + M) phase. Moreover post-irradiation cell treatment with MDI reduces the number of damaged cells.
Subject(s)
Lymphocytes/drug effects , Lymphocytes/radiation effects , Radiation-Protective Agents/pharmacology , Cells, Cultured/chemistry , Cells, Cultured/drug effects , Cells, Cultured/radiation effects , DNA/analysis , DNA/drug effects , DNA/radiation effects , Dose-Response Relationship, Radiation , Flow Cytometry , Gamma Rays , Humans , Interphase/drug effects , Interphase/radiation effects , Lymphocytes/chemistry , Micronucleus Tests , Plant Extracts , Time FactorsABSTRACT
The comparison of force-velocity (p-V) relation was made for live and chemically skinned frog skeletal muscle fibers. The latter fibers revealed steeper p-V curves. Maximal isometric tension in these fibers was 27 per cent less. The maximal velocity of unloaded shortening was 15 per cent greater.