Cytosolic free calcium concentrations in avian growth plate chondrocytes.
Isolated avian growth plate chondrocytes convert the acetoxymethyl ester (AM) form of Fura-2 quickly and efficiently to the Ca2(+)-sensitive pentacarboxylic acid (FA) form. Control experiments indicate that the Kd for intracellular Fura-2/FA is very close to that of extracellular Fura-2/FA at the same ionic strength and pH and that the Fura-2/FA fluorescence from indicator converted by intracellular organelles is quite small. Correcting for the effects of extracellular Fura-2/FA and partial hydrolysis products has improved the accuracy of determination of intracellular [Ca2+] over earlier measurements in chondrocytes. Cytosolic [Ca2+] in isolated growth plate chondrocytes (containing cells from each maturational stage) is found to require approximately 9 hours to recover from the isolation process. After this recovery period, cytosolic [Ca2+] in these cells converges to approximately 70 nM regardless of the [Ca2+] of the recovery medium, suggesting regulation of cytosolic [Ca2+] to a set point. Chondrocytes that are separated into maturationally distinct fractions using countercurrent centrifugal elutriation show an increase in cytosolic [Ca2+] with cellular maturation. The least mature resting cells have a [Ca2+] near 57 nM, while the most mature hypertrophic cells are around 95 nM.
Gunter
T E
TE
Department of Biophysics, University of Rochester, School of Medicine and Dentistry, New York.
Zuscik
M J
MJ
Puzas
J E
JE
Gunter
K K
KK
Rosier
R N
RN
D000818:Animals; D002113:Calcification, Physiologic / Q000502:physiology; D002118:Calcium / Q000032:analysis*; D002454:Cell Differentiation; D002458:Cell Fractionation; D002469:Cell Separation; D002645:Chickens; D003600:Cytosol / Q000737:chemistry*; D016257:Fura-2 / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006132:Growth Plate / Q000737:chemistry / Q000166:cytology* / Q000502:physiology; D015388:Organelles / Q000378:metabolism
C049925:fura-2-am; D002118:Calcium; D016257:Fura-2