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Microinjection of Xenopus Laevis Oocytes
Published on: February 23, 2009
Interaction between injected Ca2+ and intracellular Ca2+ stores in Xenopus oocytes
1Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
FEBS Letters
|July 2, 1990
Summary
Repeated calcium (Ca2+) injections into Xenopus oocytes enhance the chloride (Cl-) current response. This potentiation is dependent on intracellular calcium stores, suggesting their role in regulating calcium signaling.
Area of Science:
- Cellular Biology
- Biophysics
- Neuroscience
Background:
- Calcium ions (Ca2+) are critical intracellular messengers involved in numerous cellular processes.
- Xenopus oocytes are widely used model systems for studying ion channel function and calcium signaling.
Purpose of the Study:
- To investigate the phenomenon of 'potentiation' of transient chloride (Cl-) currents following repetitive deep Ca2+ injections into Xenopus oocytes.
- To elucidate the role of intracellular Ca2+ stores in this observed potentiation.
Main Methods:
- Deep injections of Ca2+ into Xenopus oocytes at varying intervals.
- Measurement of transient Cl- currents.
- Oocyte permeabilization using the ionophore A23187 in Ca2+-free solutions.
Main Results:
- The amplitude of the Cl- current induced by a second Ca2+ injection was several-fold higher than the first.
- This potentiation persisted even with 60-90 minute intervals between injections.
- Potentiation was abolished in oocytes permeabilized with A23187, with recovery after 30 minutes.
Conclusions:
- Injected Ca2+ is largely sequestered by intracellular stores.
- Subsequent Ca2+ injections lead to a higher proportion of Ca2+ reaching the membrane due to loaded stores, causing potentiation.
- Ionophore treatment disrupts store-mediated Ca2+ buffering, preventing potentiation by allowing rapid Ca2+ release and reuptake.
