Metabolic responses of isolated hepatocytes to adenosine; dependence on external calcium.
The role of cyclic-adenosine monophosphate (cAMP) and calcium (Ca2+) in the metabolic responses to adenosine was studied in isolated hepatocytes from fed rats. In the presence of 1.2 mM Ca but not in the absence of Ca2+, adenosine stimulated ureagenesis without increasing cAMP. Adenosine inhibited the glucagon mediated increase in cAMP. Adenosine increased free cytoplasmic Ca2+ provided that cells were incubated in the presence of external Ca2+. In the absence of added Ca2+ adenosine did not stimulate ureagenesis or the movements of Ca2+. It is suggested that, in the liver cell, Ca2+ may be a second messenger for adenosine.
Díaz
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School of Veterinary Medicine, Universidad Nacional Autónoma de México, México D.F.
Guinzberg
R
R
Uribe
S
S
Piña
E
E
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005934:Glucagon / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013050:Spectrometry, Fluorescence; D014508:Urea / Q000378:metabolism
D014508:Urea; D005934:Glucagon; D000242:Cyclic AMP; D000241:Adenosine; D002118:Calcium; D004837:Epinephrine