Spontaneous calcium oscillations and mechanically and chemically induced calcium responses in mammary epithelial cells.
Changes of intracellular calcium activity (Ca2+i) in mouse mammary epithelial cells in primary culture (normal) and in an established cell line (MMT060562, cancerous) were investigated by microfluorometry and image analysis of fura-2 fluorescence. In both types of cells, some populations exhibited occasional Ca2+i oscillations with a period of 50-160 s. Slight mechanical stimulation of a cell with a fine glass pipette induced a Ca2+i increase, which spread from the stimulated cell to the surrounding cells with a speed of 7-12 microns/s. ATP (> 1 mumol/l) and ADP, but not AMP induced a Ca2+i increase in both cell types. Bradykinin was highly effective (> 10 nmol/l) only in the cancerous mammary epithelial cells. In Ca(2+)-free solution, all these Ca2+i responses remained unchanged at the first application, and decreased abruptly at the second trial. La3+ (> 0.5 mmol/l) suppressed the response to ATP but not the response to bradykinin. Addition of extracellular Mn2+ rapidly quenched the fura-2 fluorescence in the cell even in a non-stimulated state. Influx of Mn2+ did not increase during Ca2+i responses. These results indicate that the sources of Ca2+i responses in mammary epithelial cells are intracellular stores, which exchange Ca2+ with the extracellular medium.
Furuya
K
K
Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
Enomoto
K
K
Yamagishi
S
S
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002712:Chlorides; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D017136:Ion Transport / Q000187:drug effects; D007811:Lanthanum / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D017895:Manganese Compounds; D051379:Mice; D008813:Mice, Inbred ICR; D010812:Physical Stimulation; D011247:Pregnancy
D002712:Chlorides; D017895:Manganese Compounds; C028521:lanthanum chloride; D008345:Manganese; D007811:Lanthanum; D000255:Adenosine Triphosphate; C025340:manganese chloride; D001920:Bradykinin; D002118:Calcium