Mechanical sensitivity of carotid body glomus cells

Abstract

Cultured glomus cells from rat carotid bodies were prepared for optical studies of intracellular calcium using the Fura-2 dye. The baseline calcium had a mean of about 40 nM showing either a relatively steady level or large calcium spikes. Some cells did not show measurable levels of [Ca(2+)](i). Stirring the fluid bathing the cultures induced large increases in [Ca(2+)](i) which were abolished when the bathing medium had zero Ca(2+) and EGTA. It is concluded that glomus cells respond to mechanical stimulation when directly exposed to this stimulus and are not protected by supporting structures. It is unknown if the electrical properties of these cells are also affected by mechanical challenges.

Figure 1

A-D, mean effects of stirring the fluid bathing cultured glomus cells on calcium influx. Solid arrows, stirring induces calcium influx. Open arrows, ineffective stirrings. A, effects on stable calcium baseline. Note reduction of effect after three stimuli. B, burst of calcium influxes after one stirring. Effect disappears in zero calcium + 1 mM EGTA. C, preparation showing spontaneous calcium spikes. Stirrings induce calcium influxes no larger than the spontaneous activity. D, calcium influx produced by stirring in preparation showing no baseline calcium. N, number of recorded cells.

Figure 2

Superimposed areas depicting calcium fluxes in four cells. Two stirrings (bottom line) separated by about 50 s induce simultaneous effects on calcium influx. Note that calcium influx occurs simultaneously in all activated cells, as in all experiments.