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21.
A membrane fraction was isolated from the smooth muscle of the pig stomach by density gradient centrifugation. It was observed that the ATP-dependent Ca uptake in this fraction was diminished if the microsomes were pelleted by differential centrifugation. The decrease of the oxalate-independent Ca uptake was relatively small, but the oxalate-stimulated Ca uptake was reduced dramatically. Evidence is presented which indicates that the selective decrease of the oxalate-stimulated Ca uptake is mainly caused by mechanical damage of the vesicles. Since the oxalate-stimulated Ca uptake can be largely preserved by avoiding pelleting during the membrane fractionation, this observation may be very useful for the further study of Ca transport in subcellular fractions of smooth muscle. 相似文献
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Tamara Kubasova Sára Antal Z. Somosy G. J. Köteles 《Radiation and environmental biophysics》1984,23(4):269-277
Summary For studies on cell membranes, mice were exposed to mixed neutron + gamma reactor-radiation in the range of total doses from 0.5 to 4.5 Gy. Changes in functional activity of plasma membranes of erythrocytes, platelets, and lymphocytes were followed by a lectin-binding technique at various intervals afterwards. The amount of3H-concanavalin A bound to cells altered considerably during the 1st h after irradiation in all cell types. Lymphocytes and platelets, however, were more sensitive than erythrocytes as increased lectin-binding could already be observed after 0.5 Gy. The binding ability of these cells performed oscillatory behaviour. In addition, alterations in shapes and ultrastructure of cell surfaces and intracellular membranes were observed. 相似文献
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Luminal Ca2+ controls the activation of the inositol 1,4,5-trisphosphate receptor by cytosolic Ca2+.
L Missiaen H De Smedt G Droogmans R Casteels 《The Journal of biological chemistry》1992,267(32):22961-22966
Luminal Ca2+ controls the sensitivity of the intracellular Ca2+ stores to inositol 1,4,5-trisphosphate (Ins(1,4,5)P3). Ins(1,4,5)P3-induced Ca2+ release is also controlled by cytosolic Ca2+; low concentrations of Ca2+ stimulate the release. The aim of this work was to investigate whether luminal Ca2+ would affect the stimulation of the Ins(1,4,5)P3 receptor by cytosolic Ca2+ in permeabilized A7r5 smooth muscle cells. We also report that the Ins(1,4,5)P3 receptor in A7r5 cells is activated by low concentrations of cytosolic Ca2+. Cytoplasmic Ca2+ increases the Ins(1,4,5)P3 sensitivity without affecting the cooperativity. The increase in Ins(1,4,5)P3 sensitivity becomes relatively more pronounced when the Ca2+ content of the stores decreases. This modulatory effect of luminal Ca2+ on the responsiveness to cytosolic Ca2+ is an intrinsic property of the Ins(1,4,5)P3 receptor. 相似文献
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Veronika Lozhnikova J. Krekule Frideta Seidlová Tamara Bavrina M. Kh. Chailakhyan 《Biologia Plantarum》1981,23(1):36-40
Abscisic acid (ABA) was applied in a concentration of 1. 10?3 M and 1. 10?4 M to the quantitative SD plantChenopodium rubrum under various light regimes. ABA did not influence flowering in plants under continuous illumination, enhanced flowering in plants subjected to long days and inhibited it in plants induced by short days. It was concluded that ABA can not substitute for inductive treatment but its action may be additive to initial stages of reproductive morphogenesis (enhanced growth rate and branching of the apical meristem) as evoked by long days. 相似文献
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Rakić Tamara Pešić Mila Kostić Nikola Andrejić Gordana Fira Djordje Dželetović Željko Stanković Slaviša Lozo Jelena 《Plant and Soil》2021,462(1-2):349-363
Plant and Soil - Flotation tailings represent an extremely unfriendly substrate for plant colonization due to toxic metal concentrations and marked macronutrient deficiencies. The perennial grass... 相似文献
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