CALCIUM UPTAKE INTO RAT PHEOCHROMOCYTOMA CELLS

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract– The uptake of 45Ca2+ into cell suspensions prepared from a transplantable rat pheochromocytoma was measured. The uptake of Ca2+ into these cells is biphasic; there is a rapid, initial uptake of Ca+, followed by a slower uptake that proceeds at a linear rate for at least 10min at 37°C. The uptake of Ca2+ is a linear function of the external Ca2+ concentration over the range of 0.13-2.5 mm-Ca2+ Incubation of the cells in a medium containing 56mm-K+ results in a 2-3 fold increase in the uptake of Ca2+ into the cells; 56mm-K+ increases both phases of Ca2+ uptake. The cells apparently lack a mechanism to inactivate this 56 mm-K+-induced increase-in Ca2+ permeability. Two inhibitors of K+ stimulated catecholamine secretion, diphenylhydantoin and verapamil, both inhibit K +-stimulated Ca2+ uptake. These results provide a direct demonstration of the stimulus-coupled uptake of Ca2+ into chromaffin cells, and provide additional evidence for the correlation of Ca2+ uptake with catecholamine secretion by these cells.

Electronic Resource