1. Mitochondrial and microsomal fractions were prepared from rat parotid glands. Both fractions were able to take up45Ca. The mitochondrial45Ca-uptake system could be driven by ATP (energy-coupled Ca2+uptake) or by ADP+succinate (respiration-coupled Ca2+uptake). Energy-coupled Ca2+uptake was blocked by oligomycin but not by carbonyl cyanide m-chlorophenylhydrazone; respiration-coupled Ca2+uptake was blocked by carbonyl cyanide m-chlorophenylhydrazone but not by oligomycin. Microsomal Ca2+uptake was dependent on the presence of ATP; the ATP-dependent Ca2+uptake was not affected by oligomycin or carbonyl cyanide m-chlorophenylhydrazone. Ca2+uptake by both fractions was inhibited by Ni2+. 2. Incubation of parotid pieces with adrenaline increased the rate of release of amylase and the uptake of45Ca. The adrenaline-stimulated release of amylase was not dependent on the presence of extracellular Ca2+. 3. The effect of adrenaline on the subcellular distribution of45Ca in parotid pieces incubated with45Ca was studied. In parotid tissue incubated with45Ca, both mitochondrial and microsomal fractions contained45Ca. Incubation with adrenaline increased the amount of45Ca incorporated into the mitochondrial fraction but not the microsomal fraction. In parotid tissue preloaded with45Ca subsequent incubation with adrenaline caused a decrease in the amount of45Ca found in both the mitochondrial and microsomal fractions. 4. From these data we conclude that the regulation of the cytosolic Ca2+concentration in the parotid may involve both mitochondrial and microsomal Ca2+-uptake systems. We suggest that the action of adrenaline on the parotid may be to increase the movement of Ca2+to the cytosol by increasing the flux of Ca2+across mitochondrial, microsomal and plasma membranes.
Effect of calcium ions on amylase release from rat parotid glands