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Calcium transport study of SF-9 lepidopteran cells and bull frog sympathetic ganglion cells





ABSTRACT The intracellular calcium level and the calcium efflux of the bull-frog sympathetic ganglion cells (BSG) and the SF-9 lepidopteran ovarian cells were investigated using a calcium-sensitive fluorescence probe fura-2. It was found that the intracellular calcium levels were 58.2 and 44.7 nM for the BSG cells and SF-9 cells respectively. The calcium effluxes following zero calcium solution were 2.02 and 1.33 fmole·cm-2·s-1 for the BSG cells and SF-9 cells. The calcium effluxes following sodium orthovanadate (Na2VO4) in zero calcium solution were 6.00 and 0.80 fmole·cm-2·s-1 for the BSG cells and the SF-9 cells. The SF-9 cells also lost the ability to extrude intracellular calcium after 2-3 applications of Na2VO4 while the BSG cells showed no apparent lost of calcium extruding abilities for up to 4 applications of Na2VO4.





INTRODUCTION



Spodoptera frugiperda clone 9 (SF-9) cells are a cultured insect cell line derived from the butterfly ovarian tissue. SF-9 cells are used by molecular biologists for the studies of gene expression and protein processing (Luckow and Summers, 1988). However, there is not much known about these cells' basic biophysiology. Since calcium is involved in many cells' activities such as acting as a secondary messenger, it is important for cells to control their intracellular calcium level. This study was aimed toward looking at the some of the basic properties of the SF-9 cells such as resting calcium concentration and rate of calcium extrusion after being calcium level being raised by an ionophore 4-bromo-A23187. The effect of sodium orthovanadate (an active transport inhibitor) on calcium extrusion was also looked at. Microspectrofluorescence techniques and the calcium-sensitive probe fura-2 were used to...