Sensitivity of the response of cytosolic calcium in Quin-2-loaded rat hepatocytes to glucagon, adenine nucleosides, and adenine nucleotides.
Hepatocytes from fasted rats were used to study the effect of glucagon on intracellular free cytosolic Ca2+ ([Ca2+]i) indicated by the use of Quin-2-calcium fluorescence. It was found that, in both male and female rats, glucagon increased [Ca2+]i at a half-maximally effective concentration (Kact) of 0.3 nM, a concentration known to be half-maximal for affecting several hepatic functions. Acute chelation of extracellular Ca2+ did not obliterate the hormone effect but shortened its duration. Cyclic AMP, 5'-AMP, ADP, and ATP also increased [Ca2+]i, while adenosine 2':3'-monophosphate and 3'-AMP did not. The rise in [Ca2+]i brought about by glucagon at near physiological concentrations may be responsible for the stimulation of glutamate metabolism produced acutely by glucagon.
D000227:Adenine Nucleotides / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D005934:Glucagon / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013050:Spectrometry, Fluorescence
D000227:Adenine Nucleotides; D000634:Aminoquinolines; D000249:Adenosine Monophosphate; D004533:Egtazic Acid; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005934:Glucagon; D000242:Cyclic AMP; C035739:Quin2; D002118:Calcium