Neuropeptides and other secretagogues in bovine chromaffin cells: their effect on opioid peptide metabolism.
Bovine adrenal medullary cells released significant amounts of opioid pentapeptides (Methionine- and Leucine-enkephalin), when stimulated with neuropeptides like angiotensin II (AT), bradykinin (BK) or neurotensin (NT). Dose-response curves for angiotensin II and bradykinin were shown to be double-sigmoidal, with the first EC50 in the nM range; much lower than that for acetylcholine, nicotine or histamine. Secretory effects were dependent on extracellular CA++ and impaired by the Ca++ channel blockers D600. Moreover, these peptides produced an increase in opioid peptide cell content after 48 h of incubation, as did nicotine-, histamine- and K+ treated cells. The compound's capacity to induce long-term Met-enk secretion was similar to their efficacy in raising intracellular opioid peptide levels, suggesting compensatory increases. Besides affecting opioid peptide metabolism, AT, BK and NT produced a significant accumulation of inositol-1-phosphates (IP1), the role of which remains to be clarified. The physiological significance of vasoactive compounds in the adrenal medulla will be discussed.
Bommer
M
M
Department of Neuropharmacology, Max-Planck-Institut für Psychiatrie, Martinsried, Federal Republic of Germany.
Herz
A
A
D000313:Adrenal Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004744:Enkephalin, Methionine / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D009538:Nicotine / Q000494:pharmacology*; D012636:Secretory Rate / Q000187:drug effects; D013997:Time Factors
D007295:Inositol Phosphates; D009479:Neuropeptides; D004744:Enkephalin, Methionine; D009538:Nicotine; D006632:Histamine; D002118:Calcium