Adenosine receptors activate adenylate cyclase and enhance secretion from bovine adrenal chromaffin cells in the presence of forskolin.
Cells of the adrenal medulla release not only catecholamines but also high concentrations of neuropeptides and nucleotides. Chromaffin cells, like many neuronal cells, have a diversity of receptors: adrenergic receptors, peptide receptors, histamine receptors, and dopamine receptors. We recently reported that these cells have nucleotide receptors that can mediate inhibition of the secretory response. The present studies show that adenosine, in the presence of enabling concentrations of forskolin, can potently enhance response to nicotinic stimulation. Neither adenosine nor forskolin alone produces a significant effect. A marked rise in intracellular cyclic AMP (cAMP) concentration is associated with the enhancement of secretion caused by forskolin plus adenosine. A phosphodiesterase inhibitor, Ro 20-1724, used together with forskolin produces significant increases in both cellular cAMP content and catecholamine secretion. However, the adenosine agonist 5'-N-ethylcarboxyadenosine elevates cellular cAMP content in the presence of forskolin without having any positive effect on secretion. This finding suggests that the rise in cAMP level may not be the sole cause of the increase in secretion by adenosine.
Chern
Y J
YJ
Department of Biochemistry, University of Massachusetts, Amherst 01003.
Kim
K T
KT
Slakey
L L
LL
Westhead
E W
EW
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D019830:Adenosine-5'-(N-ethylcarboxamide); D000262:Adenylyl Cyclases / Q000378:metabolism*; D000310:Adrenal Gland Neoplasms / Q000378:metabolism; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002838:Chromaffin System / Q000187:drug effects / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000096:biosynthesis; D004357:Drug Synergism; D004789:Enzyme Activation; D007700:Kinetics; D010766:Phosphorylation; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured
D011983:Receptors, Purinergic; D005576:Colforsin; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D019830:Adenosine-5'-(N-ethylcarboxamide); D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D000241:Adenosine