Ca2+ activates glycogenolysis in isolated mantle storage cells of Mytilus galloprovincialis Lmk.
Glycogenolytic activity (GA) in isolated mantle storage cells (MSC) from Mytilus galloprovincialis was studied, while glycogen and free-glucose content, as well as glucose released from cells were tested. In the period studied (November-December), the glucose releasing activity measured can be considered as an output of GA. In both, whole cells system (WCS) and crude cell-free system (CFS), a non-stimulated GA was detected. In WCS, dopamine and 5-hydroxytryptamine (5-HT) stimulated glycogenolysis, while epinephrine, norepinephrine and isoproterenol did not show any effect. Furthermore, mellitin and the Ca(2+)-ionophore, A23187, had a stimulating effect on the GA. In CFS, the absence of Ca2+ ions was a sufficient condition to depress GA. These and other findings suggest that: 1) GA in MSC may be stimulated by dopamine and 5-HT and not by adrenergic agonists; 2) cytosolyc Ca2+ signalling may have become an absolute requirement for activation of the glycogenolytic cascade in MSC; 3) a rapid high-affinity glucose transport may occur in these cells.
Crespo
C A
CA
Departamento de Fisiología, Facultad de Farmacia, Universidad de Santiago de Compostela, Spain.
García-Caballero
T
T
Beiras
A
A
Espinosa
J
J
D015056:1-Methyl-3-isobutylxanthine; D000818:Animals; D001679:Biogenic Amines / Q000494:pharmacology; D049872:Bivalvia / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis*; D007700:Kinetics; D008297:Male; D008555:Melitten / Q000494:pharmacology; D008854:Microscopy, Electron
D001679:Biogenic Amines; D008555:Melitten; D000001:Calcimycin; D006003:Glycogen; D005947:Glucose; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine