scholarly journals Studies on the role of calcium ions in the stimulation by adrenaline of amylase release from rat parotid

1974 ◽  
Vol 144 (3) ◽  
pp. 543-550 ◽  
Author(s):  
R L Dormer ◽  
S J H Ashcroft
Keyword(s):  
Calcium Ions ◽  
Plasma Membranes ◽  
Microsomal Fraction ◽  
Mitochondrial Fraction ◽  
Uptake System ◽  
Parotid Glands ◽  
Amylase Release ◽  
Carbonyl Cyanide ◽  
Rat Parotid

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.

scholarly journals Effect of calcium ions on amylase release from rat parotid glands

1987 ◽  
Vol 43 ◽  
pp. 204
Author(s):  
Hiroko Nomura ◽  
Masakatsu Tachibana ◽  
Takahide Nomura ◽  
Yasumichi Hagino
Keyword(s):  
Calcium Ions ◽  
Parotid Glands ◽  
Amylase Release ◽  
Rat Parotid

scholarly journals The role of calcium in the interaction of α- and β-adrenergic agonists on amylase release from rat parotid glands

1985 ◽  
Vol 39 ◽  
pp. 318
Author(s):  
Hiroko Nomura ◽  
Takahide Nomura ◽  
Hiroshi Maekawa ◽  
Ken Izuhara ◽  
Masakatsu Tachibana ◽  
...  
Keyword(s):  
Adrenergic Agonists ◽  
Parotid Glands ◽  
Amylase Release ◽  
Rat Parotid

scholarly journals Effect of calcium ions on amylase release from rat parotid glands

1986 ◽  
Vol 40 ◽  
pp. 266
Author(s):  
Hiroko Nomura ◽  
Takahide Nomura ◽  
Masakatsu Tachibana ◽  
Yasumichi Hagino
Keyword(s):  
Calcium Ions ◽  
Parotid Glands ◽  
Amylase Release ◽  
Rat Parotid

scholarly journals The Role of Calcium Ion in Methoxamine-Induced Amylase Release from Parotid Glands of Euthyroid and Hypothyroid Rats

1985 ◽  
Vol 37 (1) ◽  
pp. 134-137
Author(s):  
Yasumichi HAGINO ◽  
Hiroko NOMURA ◽  
Takahide NOMURA ◽  
Hiroshi MAEKAWA ◽  
Ken IZUHARA ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Parotid Glands ◽  
Amylase Release

scholarly journals The (Ca2+ + Mg2+)-stimulated ATPase of the rat parotid endoplasmic reticulum

1986 ◽  
Vol 235 (2) ◽  
pp. 491-498 ◽  
Author(s):  
P Thiyagarajah ◽  
S C Lim
Keyword(s):  
Endoplasmic Reticulum ◽  
Cyclic Amp ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Reductase Activity ◽  
Gradient Centrifugation ◽  
Fold Increase ◽  
Parotid Glands ◽  
Tissue Homogenates ◽  
Rat Parotid

A membrane fraction enriched in endoplasmic reticulum was prepared from rat parotid glands by using sucrose-gradient centrifugation. The fraction showed a 10-fold increase in specific activity of NADPH: cytochrome c reductase activity over that of tissue homogenates and minimal contamination with plasma membranes or mitochondria. The endoplasmic reticulum fraction possessed both Mg2+ -stimulated ATPase as well as Ca2+, Mg2+-ATPase [(Ca2+ + Mg2+)-stimulated ATPase]activity. The Ca2+, Mg2+-ATPase required 2-5 mM-Mg2+ for optimal activity and was stimulated by submicromolar concentrations of free Ca2+. The Km for free Ca2+ was 0.55 microM and the average Vmax. was 60 nmol/min per mg of protein. The Km for ATP was 0.11 mM. Other nucleotides, such as GTP, CTP or ADP, could not substitute for ATP in supporting the Ca2+-activated nucleotidase activity. Increasing the K+ concentration from 0 to 100 mM caused a 2-fold activation of the Ca2+, Mg2+-ATPase. Trifluoperazine, W7 [N-(6-aminohexyl)-5-chloronaphthalene-1-sulphonamide] and vanadate inhibited the enzyme. The concentration of trifluoperazine and vanadate required for 50% inhibition of the ATPase were 52 microM and 28 microM respectively. Calmodulin, cyclic AMP, cyclic AMP-dependent protein kinase and inositol 1,4,5-trisphosphate had no effect on the ATPase. The properties of the Ca2+, Mg2+ -ATPase were distinct from those of the Mg2+-ATPase, but comparable with those reported for the parotid endoplasmic-reticulum Ca2+-transport system [Kanagasuntheram & Teo (1982) Biochem. J. 208, 789-794]. The results suggest that the Ca2+, Mg2+-ATPase is responsible for driving the ATP-dependent Ca2+ accumulation by this membrane.

scholarly journals Ca2+-independent fusion of secretory granules with phospholipase A2-treated plasma membranes in vitro

1995 ◽  
Vol 307 (2) ◽  
pp. 563-569 ◽  
Author(s):  
T Nagao ◽  
T Kubo ◽  
R Fujimoto ◽  
H Nishio ◽  
T Takeuchi ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Secretory Granules ◽  
Fusion Process ◽  
Amylase Release ◽  
Fusogenic Activity ◽  
Rat Parotid

The fusion of secretory granules with plasma membranes prepared from rat parotid gland was studied in vitro to clarify the mechanism of exocytosis. Fusion of the granules with plasma membranes was measured by a fluorescence-dequenching assay with octadecyl rhodamine B, and release of amylase was also measured to confirm the fusion as a final step of the secretory process. Plasma membranes that had been pretreated with porcine phospholipase A2 (PLA2) in the presence of 20 microM Ca2+ fused with the granules within 30 s, and induced amylase release by reacting with the membranes of granules, whereas without this pretreatment they had no significant effect. The fusion process accompanied by amylase release was induced in the presence of 10 mM EGTA, and therefore was apparently Ca(2+)-independent. On the other hand, the presence of EGTA or 100 microM quinacrine, an inhibitor of PLA2, during treatment of plasma membranes with PLA2 inhibited their fusogenic activity, suggesting the importance of activation of PLA2. Arachidonic acid and linoleic acid were released from the plasma membranes during the PLA2 treatment. The presence of albumin, an adsorbent of fatty acids, during the treatment also inhibited the activity. Pretreatment of the membranes with arachidonic acid or linoleic acid did not have any effect, but the presence of exogenously added arachidonic acid during PLA2 treatment enhanced the membrane-fusion-inducing effect of PLA2. Pretreatment of the membranes with lysophosphatidylcholine induced fusogenic activity. These findings suggest that the conformational change in the plasma-membrane phospholipids induced by PLA2 and the presence of arachidonic acid or linoleic acid produced by PLA2 are important in the process of fusion of secretory granules with the plasma membranes of rat parotid acinar cells and that the fusion process itself is independent of Ca2+.

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