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Intracellular Ca2+ homeostasis in rat round spermatids
Biology of the Cell
|December 3, 1998
Summary
Rat round spermatids maintain intracellular calcium levels using active extrusion via plasma membrane Ca(2+)-ATPases and sarco-endoplasmic reticulum Ca(2+)-ATPases (SERCA). These cells also store and release calcium from non-mitochondrial stores.
Area of Science:
- Cell Biology
- Reproductive Biology
- Biochemistry
Background:
- Intracellular calcium ([Ca2+]i) regulates mammalian oocyte meiosis.
- The role of [Ca2+]i in spermatogenesis and its cellular homeostasis remains unclear.
Purpose of the Study:
- To investigate the role of intracellular calcium ([Ca2+]i) in regulating spermatogenesis.
- To elucidate the cellular homeostatic mechanisms of [Ca2+]i in spermatogenic cells.
Main Methods:
- Utilized intracellular fluorescent probes (fluo-3, fura-2) to measure [Ca2+]i in rat round spermatids.
- Employed immunodetection of plasma membrane (PM) Ca(2+)-ATPases.
- Investigated Ca2+ stores and release mechanisms using thapsigargin and ionomycin.
Main Results:
- Rat round spermatids maintain basal [Ca2+]i levels of approximately 60 nM.
- Active Ca2+ extrusion occurs via PM Ca(2+)-ATPases and SERCA pumps.
- Non-mitochondrial intracellular Ca2+ stores, releasable by ionomycin, were identified.
- Ca2+ entry mechanisms were not activated by the release of Ca2+ from SERCA-regulated stores.
Conclusions:
- Rat round spermatids actively regulate intracellular calcium levels.
- These cells possess functional intracellular calcium stores and extrusion mechanisms.
- Modulated intracellular calcium signals can be generated in rat spermatids.