scholarly journals Mitogenic stimulation transiently increases the exchangeable mitochondrial calcium pool in rat thymocytes

1987 ◽  
Vol 246 (1) ◽  
pp. 173-177 ◽  
Author(s):  
P L Lakin-Thomas ◽  
M D Brand
Keyword(s):  
Concanavalin A ◽  
Mitochondrial Calcium ◽  
Mitogenic Stimulation ◽  
Exchangeable Calcium ◽  
Selective Depletion ◽  
Significant Change ◽  
Calcium Pool

Exchangeable calcium pools were measured in rat thymocytes by 45Ca labelling and selective depletion of intracellular pools with oligomycin in the presence or absence of rotenone. The mitochondrial pool increased by 150% after 3 min of treatment with the mitogen concanavalin A, and decreased to zero 10 min after mitogen addition. No significant change in the ATP-dependent pool could be detected.

scholarly journals Stimulation of respiration by mitogens in rat thymocytes is independent of mitochondrial calcium

1988 ◽  
Vol 256 (1) ◽  
pp. 167-173 ◽  
Author(s):  
P L Lakin-Thomas ◽  
M D Brand
Keyword(s):  
Electron Transfer ◽  
Concanavalin A ◽  
Mitochondrial Respiration ◽  
Extracellular Calcium ◽  
Mitochondrial Calcium ◽  
Control Of Respiration ◽  
Atp Turnover ◽  
Stimulation Of ◽  
Calcium Pool

The role of calcium in the control of respiration by the mitogen concanavalin A (ConA) was investigated in rat thymocytes. ConA induced an increase in both mitochondrial respiration and the mitochondrial calcium pool. The stimulation of respiration was shown to be independent of the increase in mitochondrial calcium: the calcium pool declined after 3 min, whereas the respiration increase was persistent, and was not affected by depletion of the calcium pool or by buffering intracellular Ca2+ transients with quin2. The mitogen phytohaemagglutinin stimulated respiration to the same extent as ConA, but did not increase the mitochondrial calcium pool. In addition, respiration was unaffected by changes in the mitochondrial calcium pool induced by increasing or decreasing extracellular calcium. These results indicate that control of respiration is not located in the Ca2+-sensitive mitochondrial dehydrogenases. The ConA-induced increase in respiration could be blocked by oligomycin, suggesting control by cytoplasmic ATP turnover, and was not associated with detectable changes in NAD(P)H fluorescence, indicating a balance between increased electron transfer and increased supply of reduced substrates.

scholarly journals Erythrocyte calcium metabolism. Calcium exchange in normal and sickle-cell-anaemia erythrocytes

1976 ◽  
Vol 156 (3) ◽  
pp. 577-583 ◽  
Author(s):  
B F Cameron ◽  
P E Smariga
Keyword(s):  
Sickle Cell ◽  
Calcium Metabolism ◽  
Sickle Cell Anaemia ◽  
Similar Proportion ◽  
Exchange Equilibrium ◽  
Exchangeable Calcium ◽  
Calcium Loading ◽  
Calcium Exchange ◽  
Phosphate Buffered Saline ◽  
Calcium Pool

Under exchange conditions (no net increase in calcium), erythrocytes incubated in isoosmotic phosphate-buffered saline have an exchangeable calcium pool comprising about 10% of the total erythrocyte calcium. This pool reaches exchange equilibrium, for either inward-directed or outward-directed transfer of the 45Ca-exchange label, with a half-time of about 20 min. The uptake of Ca2+ requires phosphate, even under hypo-osmotic conditions, where the calcium loading expected as the cells swell is obtained only when phosphate is present. The phosphate requirement is not due to Ca2+ transport as a phosphate salt. This exchangeable-calcium pool is also present in sickle-cell-anemia erythrocytes, and comprises a similar proportion of total cellular calcium.

scholarly journals Membrane potential of mitochondria in intact lymphocytes during early mitogenic stimulation

1984 ◽  
Vol 217 (2) ◽  
pp. 453-459 ◽  
Author(s):  
M D Brand ◽  
S M Felber
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Concanavalin A ◽  
Mitochondrial Membrane ◽  
Ph Gradient ◽  
Electrochemical Gradient ◽  
Inner Membrane ◽  
Mitogenic Stimulation ◽  
Ion Movements

The mitochondrial membrane potential (delta psi m) in intact lymphocytes was calculated by measuring the distribution of radiolabelled methyltriphenylphosphonium cation. The value obtained was 120 mV. The pH gradient across the mitochondrial membrane in situ (delta pH m) was estimated to be 73 mV (1.2 pH units). Thus the electrochemical gradient of protons was about 190 mV. Addition of the mitogen concanavalin A did not alter delta psi m, showing that, if movement of Ca2+ across the inner membrane of lymphocyte mitochondria occurs when concanavalin A is added, it is accompanied by charge-compensating ion movements.

Mitogenic stimulation and the redistribution of concanavalin A receptors on lymphocytes

1981 ◽  
Vol 134 (2) ◽  
pp. 399-408 ◽  
Author(s):  
T. Pozzan ◽  
A.N. Corps ◽  
T.R. Hesketh ◽  
J.C. Metcalfe
Keyword(s):  
Concanavalin A ◽  
Mitogenic Stimulation ◽  
Concanavalin A Receptors

Kinetics of Calcium Metabolism in Rat Dentin and Enamel

1976 ◽  
Vol 55 (5) ◽  
pp. 836-840 ◽  
Author(s):  
Omar R. Tumilasci ◽  
Guillermo L. Alonso
Keyword(s):  
Intravenous Injection ◽  
Calcium Metabolism ◽  
Time Course ◽  
Specific Activity ◽  
Exchangeable Calcium ◽  
Accretion Rates ◽  
Kinetics Of ◽  
Pool Sizes ◽  
Calcium Pool

The time course of the specific activity of 45Ca in the dentin and enamel of rat incisors and molars was followed after an intravenous injection of the radiotracer. It was then correlated with the specific activity of 45Ca in plasma to obtain the accretion rates on the dentin of molars and incisors. The exchangeable calcium pool sizes in the dentin and the enamel of the molar were also calculated.

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