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Effects of Opiates on High‐Affinity Ca 2+ ,Mg 2+ ‐ATPase in Brain Membrane Subfractions
Author(s) -
Pillai N. P.,
Ross D. H.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb00807.x
Subject(s) - morphine , (+) naloxone , opiate , chemistry , antagonist , calmodulin , atpase , pharmacology , receptor , endocrinology , medicine , enzyme , biochemistry , biology
The effect of a single administration of morphine sulfate (15 mg/kg, s.c. or 30 mg/kg, i.p., 30 min) on Ca 2+ ‐stimulated Mg 2+ ‐dependent ATPase activity was investigated in synaptosomal plasma membranes (SPM) prepared from rat cortex. Morphine produced a significant decrease in Ca 2+ ,Mg 2+ ‐ATPase activity in synaptosomal fractions (SPM 1 + 2) known to contain a high density of opiate receptors and calmodulin‐dependent Ca 2+ ,Mg 2+ ‐ATPase. However, in another subpopulation (SPM 3) that contains fewer opiate receptors and less enzyme activity, no such decrease in the enzyme activity was observed after the opiate administration. The decrease in Ca 2+ ,Mg 2+ ‐ATPase activity seen in SPM 1 + 2 was specifically antagonized by the opiate antagonist naloxone hydrochloride (2 mg/kg, s.c.) when given 15 min before morphine administration. Mg 2+ ‐ATP‐ase was not altered either by morphine or by a naloxone‐morphine combination. These findings give further evidence for the role of intracellular Ca 2+ in mediating many of the acute effects of opiates.