Induction of exocytosis from glomus cells by incubation of the carotid body of the rat with calcium and ionophore A23187.

Carotid bodies from adult rats were electron microscopically studied after incubation in glucose-containing salt solutions containing calcium and/or ionophore A23187 or neither. In the absence of the ionophore, adding or omitting calcium had no effect on the fine structure of the glomus cells. Incubation in the medium containing both 1 mM calcium and the ionophore caused the appearance of exocytotic membrane profiles in several glomus cells. Exocytosis was not seen when only A23187 and endogenous calcium was present. For exocytosis to occur, calcium appeared to be essential and the event seemed to be due to a rise in the intracellular calcium concentration caused by the ionophore.