Faculty Opinions recommendation of Transmembrane proteoglycans control stretch-activated channels to set cytosolic calcium levels.

2018 ◽  
Author(s):  
Linda Troeberg
Keyword(s):  
Cytosolic Calcium ◽  
Stretch Activated Channels

Effect of verapamil on cytoplasmic distribution of granules and microfilaments in amphibian urinary bladder

1988 ◽  
Vol 46 ◽  
pp. 324-325
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Morphological Changes ◽  
Granular Cell ◽  
Cytosolic Calcium ◽  
Calcium Storage ◽  
Amphibian Urinary Bladder ◽  
Vesicular Membrane ◽  
High Concentrations ◽  
Cytoskeletal System

The amphibian urinary bladder has been used as a ‘model’ system for studies of the mechanism of action of antidiuretic hormone (ADH) in stimulating transepithelial water flow. The increase in water permeability is accompanied by morphological changes that include the stimulation of apical microvilli, mobilization of microtubules and microfilaments and vesicular membrane fusion events . It has been shown that alterations in the cytosolic calcium concentrations can inhibit ADH transmembrane water flow and induce alterations in the epithelial cell cytomorphology, including the cytoskeletal system . Recently, the subapical granules of the granular cell in the amphibian urinary bladder have been shown to contain high concentrations of calcium, and it was suggested that these cytoplasmic constituents may act as calcium storage sites for intracellular calcium homeostasis. The present study utilizes the calcium antagonist, verapamil, to examine the effect of calcium deprivation on the cytomorphological features of epithelial cells from amphibian urinary bladder, with particular emphasis on subapical granule and microfilament distribution.

A rhythm in the flowering response of photoperiodically-induced Pharbitis nil to agents affecting cytosolic calcium and pH

1992 ◽  
Vol 85 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Haya Friedman ◽  
Eliezer E. Goldschmidt ◽  
Hanna Spiegelstein ◽  
Abraham H. Halevy
Keyword(s):  
Cytosolic Calcium ◽  
Pharbitis Nil ◽  
Flowering Response

Hypersensitivity to Thromboxane A2 in Cholesterol-Rich Human Platelets

1990 ◽  
Vol 64 (04) ◽  
pp. 594-599 ◽  
Author(s):  
Takuya Tomizuka ◽  
Kyohei Yamamoto ◽  
Aizan Hirai ◽  
Yasushi Tamura ◽  
Sho Yoshida
Keyword(s):  
Calcium Concentration ◽  
Binding Capacity ◽  
Thromboxane A2 ◽  
Cytosolic Calcium ◽  
Cholesterol Content ◽  
Human Platelets ◽  
Dissociation Rate ◽  
Platelet Membrane ◽  
Maximal Concentration ◽  
Equilibrium Dissociation

SummaryThe effect of changes in platelet membrane cholesterol content on thromboxane A2 (TXA2)-induced platelet activation was studied. Concentrations of 9,ll-epithio-ll,12-methano-TXA2 (STA2), a stable analogue of TXA2 which can cause half-maximal aggregation and release of [14C]serotonin in cholesterol-rich platelets were significantly lower than those in cholesterol-normal platelets. STA2-induced increase in cytosolic calcium concentration and [32P]phosphatidic acid formation in cholesterol-rich platelets were significantly greater than those in cholesterol-normal platelets. The maximal concentration of binding site (Bmax) for SQ29548 was significantly increased in cholesterol-rich platelets compared with cholesterol-normal platelets, while the equilibrium dissociation rate constant (Kd) for SQ29548 did not differ between cholesterol-rich and cholesterol-normal platelets. The present study suggested that sensitivity to TXA2 was increased by the incorporation of cholesterol into platelet membrane and that the cause of hypersensitivity to TXA2 in cholesterol-rich platelets may be partly explained by an increase in binding capacity for TXA2.

Effect of calcium on transport characteristics of cultured proximal renal cells

1985 ◽  
Vol 249 (3) ◽  
pp. F346-F355
Author(s):  
L. M. Sakhrani ◽  
N. Tessitore ◽  
S. G. Massry
Keyword(s):  
Phosphate Uptake ◽  
Cytosolic Calcium ◽  
Ruthenium Red ◽  
Extracellular Calcium ◽  
Transport Processes ◽  
Renal Cells ◽  
Sodium Uptake ◽  
Calcium Loading ◽  
Sodium Dependent ◽  
Acute Changes

We examined the effects of acute changes in extracellular and intracellular calcium on transport processes in primary culture of proximal rabbit renal cells. A change in extracellular calcium from 0 to 3 mM inhibited amiloride-sensitive sodium uptake by 30%, and this effect was maximal at 1 mM calcium. Other polyvalent cations (Mn2+, Mg2+, La3+, and Ba2+) produced quantitatively similar inhibition of amiloride-sensitive sodium uptake compared with calcium. An increase in cytosolic calcium produced by calcium loading (20 mM) or by A23187 (20 microM) resulted in an inhibition of 25-40% of amiloride-sensitive sodium uptake. Moreover, quinidine (10(-4)M) and ruthenium red (3 microM), agents presumed to increase cytosolic calcium, inhibited amiloride-sensitive sodium uptake by 20-60%. Both these agents also inhibited sodium-dependent phosphate uptake by 20% but had no effect on ouabain-sensitive 86Rb+ uptake or on sodium-dependent alpha-methylglucoside uptake. Our data indicate that increases in extracellular calcium inhibit amiloride-sensitive sodium uptake and increases in cytosolic calcium inhibit sodium-dependent phosphate and amiloride-sensitive sodium uptakes. The effect of extracellular calcium may be due to charge screening and/or binding to the negatively charged plasma membrane or due to alterations in membrane fluidity.

scholarly journals Synthetic lipopeptide Pam3CysSer(Lys)4 is an effective activator of human platelets

1994 ◽  
Vol 266 (6) ◽  
pp. C1684-C1691 ◽  
Author(s):  
M. Berg ◽  
S. Offermanns ◽  
R. Seifert ◽  
G. Schultz
Keyword(s):  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Human Platelets ◽  
Cellular Effects ◽  
Prostacyclin Receptor ◽  
Serotonin Secretion ◽  
Peptide Moiety ◽  
Lipid Moiety ◽  
Molecular Masses ◽  
Aggregation Of Platelets

Lipopeptide analogues of the NH2-terminus of bacterial lipoprotein are known to induce activation of macrophages, neutrophils, and lymphocytes. We studied the effect of the lipopeptide N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteinyl-( S)-seryl-(S)-lysyl-(S)-lysyl-(S)-lysyl-(S)-lysine [Pam3CysSer(Lys)4] on several functions of human platelets. Pam3CysSer(Lys)4 led to the aggregation of platelets and induced the secretion of serotonin with an effectiveness similar to thrombin. These cellular effects of Pam3CysSer(Lys)4 were concentration dependent, being half maximal at 2-3 microM and maximal at 10-30 microM. Another lipopeptide also induced platelet aggregation and serotonin secretion but was less potent and less effective than Pam3CysSer(Lys)4. The lipid moiety and the peptide moiety of Pam3CysSer(Lys)4 alone were without any effect. Lipopeptides also stimulated tyrosine phosphorylation of several proteins with molecular masses similar to those found to be tyrosine phosphorylated in response to thrombin, and Pam3CysSer(Lys)4 led to an increase in the cytosolic calcium concentration. All studied responses of platelets to lipopeptides were inhibited by the prostacyclin receptor agonist cicaprost. Taken together, our data show that lipopeptides are effective activators of human platelets and that this activation is susceptible to the action of physiological platelet inhibitors.

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