The contribution of both extracellular and intracellular calcium to the action of alpha-adrenergic agonists in perfused rat liver.
The role of both intracellular and extracellular Ca2+ pools in the expression of alpha-adrenergic-agonist-mediated responses was examined in perfused rat liver. Responses studied included glycogenolysis, respiration, lactate and pyruvate formation, ketone-body production, changes in the cytoplasmic and mitochondrial redox ratio and cellular K+ fluxes. Each of these was shown to be dependent on the mobilization of intracellular Ca2+ and can be grouped into one of two response types. Transient responses (ion fluxes and the redox ratios) are obligatorily dependent on the mobilization of intracellular Ca2+ and occur irrespective of the extracellular Ca2+ concentration. Sustained responses, on the other hand, initially require intracellular Ca2+ and, subsequently, extracellular Ca2+. The data indicate that alpha-adrenergic agonists mobilize extracellular Ca2+ as well as intracellular Ca2+ and that both pools are required for the full expression of hormone-induced responses in rat liver.
D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008112:Liver Glycogen / Q000096:biosynthesis; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010477:Perfusion; D010656:Phenylephrine / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains
D000090:Acetoacetates; D006885:Hydroxybutyrates; D007773:Lactates; D008112:Liver Glycogen; D011773:Pyruvates; D010656:Phenylephrine; D019344:Lactic Acid; C016635:acetoacetic acid; D019289:Pyruvic Acid; D011188:Potassium; D002118:Calcium; D020155:3-Hydroxybutyric Acid