scholarly journals Requirement of Extracellular Calcium Ions for the Early Fertilization Events in the Medaka Egg. (calcium/microinjection/calcium-uptake/Oryzias latipes/sperm penetration)

1985 ◽  
Vol 27 (6) ◽  
pp. 751-762 ◽  
Author(s):  
T. IWAMATSU ◽  
T. OHTA ◽  
E. OSHIMA ◽  
T. SUGIURA
Keyword(s):  
Calcium Ions ◽  
Calcium Uptake ◽  
Oryzias Latipes ◽  
Extracellular Calcium ◽  
Sperm Penetration

Nitrendipine blocks high potassium contractures but not twitches in rat skeletal muscle

1988 ◽  
Vol 66 (9) ◽  
pp. 1210-1213 ◽  
Author(s):  
G. B. Frank ◽  
L. Konya ◽  
T. Subrahmanyam Sudha
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ions ◽  
Calcium Uptake ◽  
Channel Blocker ◽  
Mechanical Response ◽  
Extracellular Calcium ◽  
The Other ◽  
Rat Skeletal Muscle ◽  
Potassium Depolarization ◽  
High Potassium

The effects of the organic calcium channel blocker nitrendipine was tested on electrically evoked twitches and on potassium depolarization-induced contractures of rat lumbricalis muscles. Nitrendipine (10−7 to 5 × 10−5 M) blocked only the potassium contractures. It was concluded that blocking calcium uptake through the slow voltage-senstitive calcium channels during potassium depolarization blocks the mechanical response of the muscle. Thus extracellular calcium ions are required for the excitation–contraction (E–C) coupling during depolarization contractures. On the other hand, electrically evoked twitches were not affected by nitrendipine; therefore, extracellular calcium ions entering via the slow voltage-sensitive channels are not required for E–C coupling during the twitch.

The influence of extracellular calcium ions on the light response of Limulus ventral nerve photoreceptor

1979 ◽  
Vol 19 (4) ◽  
pp. 351
Author(s):  
M. Bruns ◽  
M. Giesen ◽  
G. Maaz ◽  
M. Pflaum ◽  
H. Stieve
Keyword(s):  
Calcium Ions ◽  
Light Response ◽  
Extracellular Calcium ◽  
Ventral Nerve Photoreceptor

INTRACELLULAR AND EXTRACELLULAR CALCIUM IONS IN TRANSMITTER RELEASE AT THE NEUROMUSCULAR SYNAPSE

1978 ◽  
Vol 307 (1 Calcium Trans) ◽  
pp. 583-598 ◽  
Author(s):  
R. Rahamimoff ◽  
S.D. Erulkar ◽  
A. Lev-Tov ◽  
Halina Meiri
Keyword(s):  
Calcium Ions ◽  
Transmitter Release ◽  
Neuromuscular Synapse ◽  
Extracellular Calcium

Whole-cell NMDA-evoked current in suprachiasmatic neurones of the rat: modulation by extracellular calcium ions

1997 ◽  
Vol 745 (1-2) ◽  
pp. 55-66 ◽  
Author(s):  
Stefano Alberi ◽  
Michel Dubois-Dauphin ◽  
Jean Jacques Dreifuss ◽  
Mario Raggenbass
Keyword(s):  
Calcium Ions ◽  
Extracellular Calcium ◽  
Whole Cell

Characterization of an In Vitro Model to Study the Permeability of Human Arterial Endothelial Cell Monolayers

1988 ◽  
Vol 60 (02) ◽  
pp. 240-246 ◽  
Author(s):  
Erna G Langeler ◽  
Victor W M van Hinsbergh
Keyword(s):  
Endothelial Cell ◽  
Calcium Ions ◽  
Electrical Resistance ◽  
Serum Proteins ◽  
Cell Monolayer ◽  
Extracellular Calcium ◽  
Endothelial Cell Monolayer ◽  
Passage Rate ◽  
Cell Monolayers

SummaryA model has been developed to study the transport of fluid and macromolecules through human arterial umbilical cord endothelial cell monolayers in vitro. Cells were cultured on fibronectin- coated polycarbonate filters and formed within a few days a tight monolayer, with an electrical resistance of 17 ± 4 Ohm · cm2. The cells were connected by close cell contacts with tight junctions. The passáge-rate of horse radish peroxidase (HRP) through these filters was 20-40 fold lower than through filters without an endothelial monolayer. The continuous presence of 10% human serum was needed to maintain the electrical resistance of the monolayer and its barrier function towards macromolecules. Chelation of extracellular calcium resulted in an increased permeability and a decreased electrical resistance of the monolayer. This process was reversible by re-addition of calcium ions to the cells. The permeation rate of dextrans of various molecular weights (9-480 kD) was inversely related to the molecular mass of the molecule. No difference was measured between the passage rate of dextran of 480 kD and dextran of 2,000 kD. Incubation of the endothelial cell monolayer with 2-deoxy-D-glucose resulted in a decreased permeability but it had no effect on electrical resistance. This suggests that the passage-process is energy- dependent.Fluid permeation through the endothelial cell monolayer on filters was measured in a perfusion chamber under 20 mmHg hydrostatic pressure. It was decreased by the presence of serum proteins and responded reversibly on the chelation and readdition of extracellular calcium ions.

The Effects of Citrate and Extracellular Calcium Ions on the Platelet Release Reaction Induced by Adenosine Diphosphate and Collagen

1979 ◽  
Vol 42 (02) ◽  
pp. 778-793 ◽  
Author(s):  
Stanley Hepinstall ◽  
Patricia M Taylor
Keyword(s):  
Calcium Ions ◽  
Sodium Citrate ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Extracellular Calcium ◽  
Release Reaction ◽  
Calcium Dependent ◽  
Platelet Release ◽  
Dependent Mechanism

SummaryThe ADP-induced release of 3H-serotonin from human platelets in heparinized platelet rich plasma is markedly stimulated by the addition of sodium citrate. The aggregation and release that is induced by collagen is less affected by citrate. Data is presented that supports the view that the effects of citrate on both ADP-and collagen-induced release are largely via alteration of the concentration of ionized calcium in plasma.Collagen can induce release of 3H-serotonin via extracellular calcium-independent and -dependent mechanisms. The possibility that the calcium-dependent mechanism is aggregation-dependent and that the calcium is required for platelet aggregation rather than directly involved in the release reaction is discussed.

Selective Abolition of Sarcoplasmic Reticulum Vesicles’ Calcium Releasing Mechanisms

1986 ◽  
Vol 41 (5-6) ◽  
pp. 652-656 ◽  
Author(s):  
Wilhelm Hasselbach ◽  
Martina Ungeheuer ◽  
Andrea Migala ◽  
Karl Ritter
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Ions ◽  
Sucrose Gradient ◽  
Calcium Uptake ◽  
Calcium Release ◽  
Salt Medium ◽  
Calmodulin Antagonists ◽  
High Concentrations ◽  
Releasing Effect

The ability of calcium lo ad ed heavy sarcoplasmic reticulum vesicles to specifically respond to the addition of various agents such as caffeine, calcium ions and calmodulin antagonists to rapidly released calcium can largely be diminished by passing the vesicular suspension in 0.3 м sucrose, 0.6 m KCl, 4 mм C Cl2, pH 7.0 through a Sepharose 6 B column or by centrifuging it through a sucrose gradient prepared with the same salt medium. Inactivation of calcium release does neither interfere with calcium uptake nor with the unspecific releasing effect caused by the application of high concentrations of calmodulin antagonists.

The interaction of calcium and hydrogen ions in the nodulation of subterranean clover

1958 ◽  
Vol 9 (4) ◽  
pp. 464 ◽  
Author(s):  
JF Loneragan ◽  
EJ Dowling
Keyword(s):  
Calcium Ions ◽  
Calcium Concentration ◽  
Calcium Uptake ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Large Degree ◽  
Hydrogen Ions ◽  
Measurable Effect ◽  
Water Culture ◽  
Calcium Requirement

A study was made of the effects of calcium and hydrogen ions on the nodulation of subterranean clover (Trifolium subterraneum L.) in water culture. A compound interaction was found. At pH 4.0 or less no nodules were formed at any calcium concentration. At a 0.01mM calcium concentration no nodules were formed at any pH used. Above these critical values, almost maximum nodulation could be obtained by an increase in either calcium concentration or pH, so that each factor was to a large degree replaceable by the other. Calcium and hydrogen ions in the range of concentrations which produced these marked interactions on nodulation had no measurable effect on plant growth (nitrate was supplied in solution). The effects of calcium and hydrogen ions on the growth of the Rhizobium strain used were also markedly different from their effects on nodulation. Hydrogen ions had a dominating effect on Rhizobium growth, while calcium ions had no effect at any pH and were required at most in trace amounts. Hydrogen ions depressed calcium uptake by the plants. It is suggested that, in the range of concentrations where they were replaceable, the effects of calcium and hydrogen ions on nodulation were through their influence on the level of calcium in the plants. It is concluded that the calcium requirement for nodulation of subterranean clover is higher than for growth of the host plant or for growth of Rhizobium.

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