Morphine coupling to invertebrate immunocyte nitric oxide release is dependent on intracellular calcium transients.
Morphine significantly stimulated invertebrate immunocyte intracellular calcium level increases in a concentration-dependent manner in cells preloaded with Fura 2/AM. Morphine's action was blocked by prior exposure of the cells to the opiate receptor antagonist naloxone. Various opioid peptides did not exhibit this ability, indicating a morphine-mu 3 mediated process. In comparing the sequence of events concerning morphine's action in stimulating both [Ca2+]i and NO production in these cells, we found that the first event precedes the second by 42 +/- 7 s. The opiate stimulation of [Ca2+]i- was attenuated in cells leached of calcium. strongly suggesting that intracellular calcium levels regulate cNOS activity in invertebrate immunocytes.
Nieto-Fernandez
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FE
Neuroscience Research Institute, State University of New York at Old Westbury 11568-0210, USA. nietof@oldwestbury.edu
Mattocks
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D
Cavani
F
F
Salzet
M
M
Stefano
G B
GB
D000818:Animals; D049872:Bivalvia; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology; D016257:Fura-2; D006434:Hemocytes / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D015398:Signal Transduction
D004745:Enkephalins; D009292:Narcotic Antagonists; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009569:Nitric Oxide; D009270:Naloxone; D009020:Morphine; D019001:Nitric Oxide Synthase; D002118:Calcium; D016257:Fura-2