Inner mitochondrial membrane potential (DeltaPsim), cytoplasmic ATP content and free Ca2+ levels in metaphase II mouse oocytes.
BACKGROUND
The relative magnitude of the inner mitochondrial membrane potential (DeltaPsim) has been suggested to indicate the competence of mammalian gametes and early embryos. This study examined the response of cultured somatic cells and mouse oocytes to inhibitors and conditions that affect DeltaPsim or metabolism, or both, and measured treatment-specific changes in ATP and cytoplasmic free Ca(2+).


METHODS
During and after treatment, relative DeltaPsim, free Ca(2+), and ATP levels and cortical granule density were determined.


RESULTS
Comparable responses of somatic cells and metaphase II mouse oocytes to experimental manipulations that affect DeltaPsim and metabolism were observed and reversible loss of DeltaPsim was associated with increased intracellular free Ca(2+), which in certain instances resulted in parthenogenetic activation.


CONCLUSIONS
The findings support a mitochondrial basis for pericortical J-aggregate fluorescence but not for a direct association between high DeltaPsim and metabolism. The results extend previous findings indicating that high-polarized (high DeltaPsim, JC-1 J-aggregate-forming) mitochondria occur in pericortical domains in mouse and human oocytes and early preimplantation stage embryos and support the notion that this spatial distribution may be related to localized ionic and metabolic regulation.
Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. vanblerk@spot.colorado.edu
Jonathan
J
Van Blerkom
Patrick
P
Davis
Samuel
S
Alexander
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001562:Benzimidazoles; D001865:Bongkrekic Acid / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002232:Carbocyanines; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials; D008677:Metaphase / Q000502:physiology*; D051379:Mice; D008928:Mitochondria / Q000502:physiology*; D009840:Oligomycins / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013696:Temperature
D001562:Benzimidazoles; D002232:Carbocyanines; D005456:Fluorescent Dyes; D007476:Ionophores; D009840:Oligomycins; D001865:Bongkrekic Acid; C068624:5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000001:Calcimycin; D000255:Adenosine Triphosphate; D002118:Calcium