Carboxyeosin decreases the rate of decay of the [Ca2+]i transient in uterine smooth muscle cells isolated from pregnant rats
Autor: | David A. Eisner, A. V. Shmigol, Susan Wray |
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Rok vydání: | 1998 |
Předmět: |
Physiology
Clinical Biochemistry Stimulation Calcium-Transporting ATPases Indo-1 Calcium in biology Sodium-Calcium Exchanger chemistry.chemical_compound Sarcolemma Pregnancy Physiology (medical) Extracellular Myocyte Animals Enzyme Inhibitors Rats Wistar Chemistry Sodium Uterus Depolarization Muscle Smooth Rats Calcium ATPase Biochemistry Biophysics Eosine Yellowish-(YS) Calcium Female Intracellular |
Zdroj: | Pflugers Archiv : European journal of physiology. 437(1) |
ISSN: | 0031-6768 |
Popis: | In myometrial smooth muscle cells the rate of decline of intracellular calcium ([Ca2+]i) is determined by Ca2+ extrusion from the cell and uptake into intracellular stores. The relative quantitative contribution of these processes however, has not been established. We therefore examined the effect of the sarcolemmal Ca2+ pump inhibitor, carboxyeosin, on the rate of the [Ca2+]i transient decline in myocytes isolated from pregnant rat uterus. Indo-1 was used in conjunction with the whole-cell patch-clamp technique to measure [Ca2+]i simultaneously with transmembrane calcium current (ICa). [Ca2+]i transients were elicited by repetitive membrane depolarization to simulate the natural pattern of uterine electrical activity. The rate of [Ca2+]i removal was calculated from the falling phase of the [Ca2+]i transient. Pre-treatment of the cells with 2 microM carboxyeosin led to a marked decrease in the rate of [Ca2+]i transient decay, suggesting that the sarcolemmal Ca2+ pump is involved in the calcium extrusion process. Removal of the extracellular Na also decreased the rate of [Ca2+]i decay, indicating an important role for the Na+/Ca2+ exchange. When both the sarcolemmal Ca2+ pump and Na+/Ca2+ exchange were inhibited the cell failed to restore [Ca2+]i after the stimulation. Comparison of the rate constants of [Ca2+]i decay in control conditions and after carboxyeosin treatment shows that approximately 30% of [Ca2+]i decay is due to the sarcolemmal calcium pump activity. The remaining 70% can be attributed to the activity of Na+/Ca2+ exchanger and the intracellular calcium stores. |
Databáze: | OpenAIRE |
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