Oscillation of Intracellular Free Calcium in Cleaving and Cleavage-Arrested Embryos of Xenopus laevis

1993 ◽  
Vol 160 (2) ◽  
pp. 512-518 ◽  
Author(s):  
H.Y. Kubota ◽  
Y. Yoshimoto ◽  
Y. Hiramoto
Keyword(s):  
Xenopus Laevis ◽  
Intracellular Free Calcium ◽  
Free Calcium

Intracellular free calcium oscillations in normal and cleavage-blocked embryos and artificially activated eggs of Xenopus laevis

1994 ◽  
Vol 107 (8) ◽  
pp. 2229-2237 ◽  
Author(s):  
T.J. Keating ◽  
R.J. Cork ◽  
K.R. Robinson
Keyword(s):  
Xenopus Laevis ◽  
Photon Counting ◽  
Calcium Oscillations ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Counting System ◽  
Normal Medium ◽  
Sinusoidal Oscillations ◽  
Cyclic Changes ◽  
Xenopus Laevis Embryos

We have measured levels of intracellular free calcium ([Ca2+]i) in albino Xenopus laevis embryos using recombinant aequorin and a photon-counting system. We observed sinusoidal oscillations in [Ca2+]i that had the same frequency as cleavage, with cleavage occurring when [Ca2+]i was lowest. An increase in calcium was seen to precede first cleavage. The cyclic changes in calcium were superimposed on a secondary pattern that increased, peaked between third and fifth cleavages and then slowly declined to a level similar to that measured before first cleavage. The amplitude of the oscillations was small during the first few cleavages but became larger with each cycle, with the largest oscillations occurring when the secondary pattern peaked (between third and fifth cleavage). As the secondary pattern declined, the amplitude of the oscillations also became smaller. The oscillations are due to release of calcium from intracellular stores, since the signal was the same in calcium-free solution as in normal medium. When cleavage was blocked with the microtubule-disrupting drugs colchicine or nocodazole, the [Ca2+]i oscillations persisted. Calcium oscillations of a similar magnitude and frequency were also present in artificially activated eggs. The secondary pattern was different in cleavage-blocked embryos and artificially activated eggs, the baseline increasing until about the third cycle and then remaining elevated for the rest of the recording (> 8 hours). By fixing embryos at various points in the calcium cycle, we determined that mitosis began shortly after calcium levels reached their peak and was complete before the calcium level dropped to its lowest point.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Superoxide anion increases intracellular free calcium in human myometrial cells.

1990 ◽  
Vol 265 (36) ◽  
pp. 22533-22536
Author(s):  
N Masumoto ◽  
K Tasaka ◽  
A Miyake ◽  
O Tanizawa
Keyword(s):  
Superoxide Anion ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Myometrial Cells

Growth and differentiation stimuli induce different and distinct increases in intracellular free calcium in human keratinocytes

1993 ◽  
Vol 284 (8) ◽  
pp. 445-450 ◽  
Author(s):  
G. R. Sharpe ◽  
C. Fisher ◽  
J. I. Gillespie ◽  
J. R. Greenwell
Keyword(s):  
Human Keratinocytes ◽  
Intracellular Free Calcium ◽  
Free Calcium

A Wave of elevated intracellular free calcium spreads through human neutrophils during phagocytosis of zymosan

1992 ◽  
Vol 51 (5) ◽  
pp. 437-443 ◽  
Author(s):  
J. Conrad Schwab ◽  
Denis A. Leong ◽  
Gerald L. Mandell
Keyword(s):  
Intracellular Free Calcium ◽  
Human Neutrophils ◽  
Free Calcium
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