Active chloride secretion by rabbit colon: Calcium-dependent stimulation by ionophore A23187

1977 ◽  
Vol 35 (1) ◽  
pp. 175-187 ◽  
Author(s):  
Raymond A. Frizzell
Keyword(s):  
Chloride Secretion ◽  
Ionophore A23187 ◽  
Calcium Dependent ◽  
Rabbit Colon

AlF 4 ? and vanadate stimulate chloride secretion in rabbit colon by a Ca2+-dependent mechanism

1992 ◽  
Vol 420 (5-6) ◽  
pp. 515-521 ◽  
Author(s):  
J. S. Jung ◽  
T. H. Hwang ◽  
D. K. Jung ◽  
Y. K. Kim ◽  
S. H. Lee
Keyword(s):  
Chloride Secretion ◽  
Rabbit Colon ◽  
Dependent Mechanism

Release of 86Rb from rat submandibular gland slices: relation to sodium pump activity

1984 ◽  
Vol 246 (5) ◽  
pp. G484-G491 ◽  
Author(s):  
D. J. Stewart ◽  
M. Laansoo ◽  
A. K. Sen
Keyword(s):  
Submandibular Gland ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Chloride Ions ◽  
Detectable Effect ◽  
Ionophore A23187 ◽  
Tissue Slices ◽  
Release Process ◽  
Calcium Dependent ◽  
Rat Submandibular Gland

Slices of rat submandibular gland were preloaded with 86Rb, an isotope that can substitute for K+ in the K+ release process. The efflux of 86Rb was monitored in a superfusion apparatus that efficiently removed the 86Rb as it exited from the tissue slices. Carbachol and the calcium ionophore A23187 activated a calcium-dependent increase in 86Rb efflux. Dibutyryl cGMP had no detectable effect on 86Rb efflux in contrast to its activation of ouabain-sensitive uptake of 86Rb observed in an earlier study. The stimulated release of 86Rb was not dependent on the presence of either sodium or chloride ions. When 86Rb efflux was stimulated by carbachol, the efflux rate returned toward the basal rate after a few minutes of exposure to carbachol in the medium. If ouabain was then introduced into the superfusate, a large increase in efflux was stimulated. In the absence of carbachol, only a small increase in 86Rb efflux was stimulated by ouabain. The effect of ouabain indicates that there was a substantial recycling of 86Rb between the release and uptake processes in the extracellular space of the tissue slice. The significance of this observation is discussed.

Low concentrations of A23187 increase calcium uptake by cardiac sarcoplasmic reticulum

1985 ◽  
Vol 249 (6) ◽  
pp. H1211-H1215
Author(s):  
J. J. Murray ◽  
A. V. Kuzmin ◽  
P. W. Reed ◽  
D. O. Levitsky
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Uptake ◽  
Atp Hydrolysis ◽  
Ionophore A23187 ◽  
Uptake System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Calcium Dependent ◽  
Uptake Measurement

The divalent cation ionophore A23187 at a concentration of 1 nM produced an increased rate of oxalate-supported calcium uptake by isolated cardiac sarcoplasmic reticulum as determined by absorbance changes of the calcium-sensitive dye murexide. Addition of a higher concentration of A23187 (0.1 microM) produced a decreased rate of calcium uptake. Measurement of the time during which ATPase was activated by calcium addition also suggested an increased rate of calcium uptake in the presence of 1 nM A23187 and an inhibition of calcium uptake at a higher concentration of the ionophore (0.1 microM). Ca2+-stimulated ATPase activity and incorporation of 32Pi from [gamma-32P]ATP into sarcoplasmic reticular proteins were increased by A23187 at concentrations of 1 nM or greater. An increased coupling of calcium uptake to ATP hydrolysis was observed at 1 nM A23187, while concentrations of the ionophore greater than or equal to 10 nM produced a decreased coupling. Addition of an inhibitor of cyclic AMP-dependent protein kinase decreased the rate of calcium uptake, and this inhibition was reversed in a concentration-dependent manner by 0.01–1 nM A23187. These data suggest that A23187 can activate a mechanism involving the calcium-dependent phosphorylation of protein that may regulate the activity of the calcium uptake system of the sarcoplasmic reticulum. These observations appear to provide an explanation for some of the contractile effects of A23187 in intact cardiac muscle that suggest that treatment with the ionophore results in an increased sequestration of calcium from the cytoplasm.

47 Calcium dependent ionophore A23187 induced eosinophil degranulation and cytolysis

1985 ◽  
Vol 75 (1) ◽  
pp. 116
Author(s):  
T FUKUDA ◽  
S ACKERMAN ◽  
C REED ◽  
M PETERS ◽  
S DUNNETTE ◽  
...  
Keyword(s):  
Ionophore A23187 ◽  
Calcium Dependent ◽  
Eosinophil Degranulation

scholarly journals Proteolytic cleavage of human von Willebrand factor induced by enzyme(s) released from polymorphonuclear cells

Blood ◽  
1986 ◽  
Vol 67 (5) ◽  
pp. 1281-1285
Author(s):  
EA Thompson ◽  
MA Howard
Keyword(s):  
Von Willebrand Factor ◽  
Cell Activation ◽  
Calcium Ionophore ◽  
Ionophore A23187 ◽  
Polymorphonuclear Cells ◽  
Dependent Manner ◽  
Calcium Dependent ◽  
Von Willebrand ◽  
Willebrand Factor

In vivo fragmentation of the von Willebrand factor antigen (vWF:Ag) molecule has been demonstrated on radiocrossed immunoelectrophoresis (CIE) in the plasma from patients with disseminated intravascular coagulation, in factor VIII concentrates, and in normal serum. Experiments reported here show that polymorphonuclear (PMN) cells contain a non-calcium-dependent protease(s) that when released and incubated with vWF:Ag results in an additional vWF:Ag peak on radio- CIE. Production of fragments of vWF:Ag by incubation with PMN cells occurred in a time-dependent manner. The protease(s) responsible was inhibited by diisopropyl fluorophosphate, soybean trypsin inhibitor, and aprotinin, but not by benzamidine, azide, epicron, or hirudin. Citrate, EDTA, and leupeptin also had no effect on the PMN cell enzyme's activity, indicating that the enzyme(s) is not calcium dependent. The PMN cell enzyme responsible for vWF:Ag fragmentation is located intracellularly and released by freezethaw lysis or cell activation by calcium or the calcium ionophore A23187.

scholarly journals Calcium-dependent proteolysis of actin during storage of platelet concentrates

Blood ◽  
1989 ◽  
Vol 73 (5) ◽  
pp. 1380-1385 ◽  
Author(s):  
EL Snyder ◽  
WC Horne ◽  
P Napychank ◽  
FS Heinemann ◽  
B Dunn
Keyword(s):  
Peptide Mapping ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Partial Purification ◽  
Ionophore A23187 ◽  
Platelet Concentrates ◽  
Storage Lesion ◽  
Calcium Dependent ◽  
Platelet Storage Lesion ◽  
Protease Degradation

Abstract In an ongoing study of the changes that occur in platelet concentrates during storage, we investigated two 28–26-Kd proteins designated SP–1 and SP–2, respectively, which increase markedly during blood-bank storage of platelet concentrates at room temperature. Formation of SP–1 and SP–2 was inhibited by storage at 4 degrees C as well as by treatment of the concentrates with leupeptin, N–ethylmaleimide, and EDTA; DFP and PPACK had no effect. The calcium ionophore A23187 markedly stimulated production of SP–1 and SP–2. After partial purification, the two proteins were found to be associated with platelet cytoskeletal protein. Two-dimensional peptide mapping and amino acid sequencing identified SP-1 and SP-2 as fragments of actin formed by cleavage on the N-terminal side of residues Thr–106 and Ala- 114, respectively. Generation of SP–1 and SP–2 during storage of platelet concentrate is likely attributable to calcium-dependent neutral protease degradation of actin and may have implications for development of the platelet storage lesion.

scholarly journals Stabilization of the shape of sickled cells by calcium and A23187

Blood ◽  
1976 ◽  
Vol 48 (6) ◽  
pp. 899-909 ◽  
Author(s):  
MR Clark ◽  
AC Greenquist ◽  
SB Shohet
Keyword(s):  
Cell Shape ◽  
Ionophore A23187 ◽  
Morphological Criterion ◽  
Calcium Dependent ◽  
Sickle Cells ◽  
Characteristic Morphology ◽  
Stabilizing Effect ◽  
Additional Support ◽  
Determining Factor

Abstract Evaluation of the role of calcium in irreversible sickling has been approached by treating sickled cells with calcium and the ionophore A23187. A calcium-dependent stabilization of the sickled cell shape was observed after reoxygenation of cells in the presence of ionophore. At low calcium concentrations, this retention of sickled shape was maintained for periods up to 1 hr. However, the morphology of the oxygen-stable sickled cells was like that of deoxygenated sickle cells and significantly different from the characteristic morphology of native irreversibly sickled cells (ISCs). Because the stabilized cells did not fulfill the morphological criterion for ISCs, the shape- stabilizing effect of calcium in this system did not provide additional support for the hypothesis that calcium accumulation was the determining factor in ISC generation.

Sign in / Sign up

Export Citation Format

Share Document