Send to

Choose Destination
J Cell Physiol. 1988 May;135(2):269-76.

Studies on the increase in cytosolic free calcium induced by epidermal growth factor, serum, and nucleotides in individual A431 cells.

Author information

Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.


The response of cytosolic calcium [Ca2+]i to epidermal growth factor (EGF), fetal calf serum, and nucleotides was determined in individual A431 cells, using the fluorescent probe fura-2 and quantitative digital video fluorescence microscopy. In the presence of 1 mM external Ca2+, EGF caused a rapid rise in [Ca2+]i, followed by a slower and variable decrease. The cells responded after a lag that varied from 10 to 30 seconds, and there was considerable cell-to-cell variation in extent of the rise in [Ca2+]i. A second challenge with EGF gave negative results. No response was obtained in nominally Ca2+-free medium supplemented with 100 microM EGTA. Somewhat similar results were obtained with fetal calf serum except that a rise in [Ca2+]i was observed both in the presence and absence of external Ca2+. The A431 cells responded to external ATP with a rise in [Ca2+]i in less than 10 seconds, both in Ca2+-containing and Ca2+-free media. A coverslip with attached cells was mounted on a small chamber, allowing complete change of medium in 2 seconds. A nearly full response was obtained with only 10 seconds of contact of cells with ATP-containing medium. After washing out ATP, there was little or no response to a second addition given 100 seconds after the first. However, a second response was obtained when the concentration of agonist was increased 10-20-fold. These data favor the idea of receptor desensitization. Both homologous and heterologous receptor desensitization was observed. A transient rise in [Ca2+]i was also noted with UTP, while ITP and CTP were inactive.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center