The role of adrenergic agonists on glycogenolysis in rat hepatocyte cultures and possible involvement of NO.
Certain liver metabolic diseases point to the presence of disturbances in glycogen deposition. Epinephrine raises the cAMP level that activates protein kinase A leading to the activation of phosphorylase and glycogen breakdown. In the present report, we sought to investigate whether NO is produced during adrenoceptor agonist-induced glycogenolysis in rat hepatocytes in cultures. Isolated glycogen rich rat hepatocytes in cultures were used. NO production (NO(2)(-)) was assessed under the effect of adrenergic agonists and adrenergic agonist/antagonist pairs, dibutyryl cyclic AMP sodium-potassium salt (db-cAMP), NO synthase (NOS) inhibitors N(omega)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine (AG) and the NO donor S-nitroso-N-acetyl penicillamine (SNAP). The inducible NO synthase (iNOS) mRNA was examined by the reverse transcription-polymerase chain reaction (RT-PCR). Glycogenolysis was quantified by glucose levels released into medium. The amount of glucose and NO(2)(-) released by hepatocytes was increased as a result of epinephrine, phenylephrine or db-cAMP treatments. The increase in glucose and NO(2)(-) released by epinephrine or phenylephrine was blocked or reduced by prazosin pretreatment and by NOS inhibitors aminoguanidine and L-NAME. iNOS gene expression was up-regulated by epinephrine. It can be concluded that glycogenolysis occurs through -adrenoceptor stimulation and a signaling cascade may involve NO production.
Hodis
J
J
Institute of Pharmacology; First Faculty of Medicine, Charles University, Prague, Czech Republic. hodik@volny.cz
Kutinová-Canová
N
N
Potmesil
P
P
Kameníková
L
L
Kmoníčková
E
E
Zídek
Z
Z
Farghali
H
H
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D003563:Cyclic CMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004837:Epinephrine / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D050261:Glycogenolysis / Q000187:drug effects*; D006146:Guanidines / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D010656:Phenylephrine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011941:Receptors, Adrenergic / Q000187:drug effects* / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D013997:Time Factors
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004791:Enzyme Inhibitors; D006146:Guanidines; D020030:Nitric Oxide Donors; D011941:Receptors, Adrenergic; D010656:Phenylephrine; D009569:Nitric Oxide; D003563:Cyclic CMP; C053441:dibutyryl cyclic-3',5'-cytidine monophosphate; D026423:S-Nitroso-N-Acetylpenicillamine; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D005947:Glucose; C004479:pimagedine; D019331:NG-Nitroarginine Methyl Ester; D011224:Prazosin; D004837:Epinephrine