Bioenergetics and mitochondrial transmembrane potential during differentiation of cultured osteoblasts.
To evaluate the relationship between osteoblast differentiation and bioenergetics, cultured primary osteoblasts from fetal rat calvaria were grown in medium supplemented with ascorbate to induce differentiation. Before ascorbate treatment, the rate of glucose consumption was 320 nmol. h(-1). 10(6) cells(-1), respiration was 40 nmol. h(-1). 10(6) cells(-1), and the ratio of lactate production to glucose consumption was approximately 2, indicating that glycolysis was the main energy source for immature osteoblasts. Ascorbate treatment for 14 days led to a fourfold increase in respiration, a threefold increase in ATP production, and a fivefold increase in ATP content compared with that shown in immature cells. Confocal imaging of mitochondria stained with a transmembrane potential-sensitive vital dye showed that mature cells possessed abundant amounts of high-transmembrane-potential mitochondria, which were concentrated near the culture medium-facing surface. Acute treatment of mature osteoblasts with metabolic inhibitors showed that the rate of glycolysis rose to maintain the cellular energy supply constant. Thus progressive differentiation coincided with changes in cellular metabolism and mitochondrial activity, which are likely to play key roles in osteoblast function.
Komarova
S V
SV
Life Sciences Division, NASA Ames Research Center, Moffett Field, California 94035-1000, USA.
Ataullakhanov
F I
FI
Globus
R K
RK
D000255:Adenosine Triphosphate / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism / Q000494:pharmacology; D001562:Benzimidazoles; D002232:Carbocyanines; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors; D004734:Energy Metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D006019:Glycolysis / Q000187:drug effects; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D011190:Potassium Cyanide / Q000494:pharmacology; D051381:Rats; D019810:Sodium Azide / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology
D001562:Benzimidazoles; D002232:Carbocyanines; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; C068624:5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine; D000255:Adenosine Triphosphate; D012969:Sodium Fluoride; D019810:Sodium Azide; D003576:Electron Transport Complex IV; D000469:Alkaline Phosphatase; D011190:Potassium Cyanide; D001205:Ascorbic Acid