Role of calcium in the phenylephrine-induced activation of phosphorylase "A" in isolated liver cells |
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| Authors: | J M Saz C Gonzalez-Manchon M S Ayuso R Parrilla |
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| Institution: | Endocrine Physiology Unit, Centro de Investigaciones Biológicas, Madrid, Spain. |
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| Abstract: | The ability of phenylephrine to activate phosphorylase in liver cells with variable degrees of Ca2+ loading was studied. Phenylephrine has been found to be capable of stimulating phosphorylase at saturating Ca2+ concentrations that precluded any further action of this ion. Furthermore the degree of activation was proportional to the cellular calcium content. These results allow to conclude that alpha-adrenergic agonists activate phosphorylase by a mechanism apparently unrelated to their ability to mobilize and subsequently increase the cytosolic concentration of free Ca2+. |
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