Passive Ca2+ transport in a suspension of isolated smooth-muscle cells and the contribution of the basal calcium permeability of the plasma membrane to the activation of a tonic contraction

• Published in: Izvestiia Akademii nauk SSSR. Seriia biologicheskaia no. 3; p. 383
• Main Authors: Shinlova, O P, Fomin, V P, Burdyga, F V, Kosterin, S A
• Format: Journal Article
• Language: Russian
• Published: Russia (Federation) 01-05-1990
• Subjects: Animals; Biological Transport - drug effects; Biological Transport - physiology; Calcium - metabolism; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Membrane Permeability - drug effects; Cell Membrane Permeability - physiology; Dose-Response Relationship, Drug; Female; In Vitro Techniques; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Myometrium - drug effects; Myometrium - metabolism; Nitrendipine - pharmacology; Rabbits; Suspensions; Vanadates - pharmacology
• ISSN: 0002-3329

Ca2+ concentration has been estimated in isolated myometrium cells using Ca2(+)-sensitive quin-2 fluorescent probe. Two components of Ca permeability of the plasmatic membrane have been determined, a potential-independent one (activated by K+ depolarization and nitrendipine-sensitive), and a basal one (not sensitive to nitrendipine). Smooth muscle cells could maintain intracellular Ca2+ concentration at the physiological level. In the presence of nitrendipine, orthovanadate, an inhibitor of sarcolemma Ca pump, induced the increase in the basal tonus depending on the presence of the Ca2+ in the medium. This suggests that in conditions of the blockage of electrically controlled Ca channels and Ca pump of the plasmatic membrane, the noncompensated basal Ca2+ influx activates the tonic contraction of smooth muscles.