Regulation of calcium handling by rat parotid acinar cells

Summary Salivary gland fluid secretion following neurotransmitter stimulation is Ca²⁺-dependent. We have studied the control of cellular Ca²⁺ following secretory stimuli in rat parotid gland acinar cells. After muscarinic-cholinergic receptor activation, cytosolic Ca²⁺ is elevated 4–5 fold, due to both intracellular Ca²⁺ pool mobilization and extracellular Ca²⁺ entry. Fluid movement ensues due to the Ca²⁺-activated enhancement of membrane permeability to K⁺ and Cl^–. Basal cytosolic Ca²⁺ levels are tightly controlled at 150–200 nM through the action of high affinity and high capacity ATP-dependent Ca²⁺ transporters in the basolateral and endoplasmic reticulum membranes. Activity of these Ca²⁺ transporters can be modulated to facilitate rapid responsiveness and a sustained fluid secretory response necessary for alimentary function.