Effects of morphine tolerance and dependence on Mg++ dependent ATPase activity of synaptic vesicles

Hiroaki Yamamoto, R. A. Harris, H. H. Loh, E. L. Way

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The effect of morphine on ATPase of synaptic plasma membranes (SPM) and synaptic vesicles isolated from the mouse brain was studied. The activity of synaptic vesicle Mg++-dependent ATPase from mice rendered morphine tolerant and dependent by pellet implantation was 40% higher than that from placebo implanted mice. However, the activities of Mg++-dependent ATPase and Na+, K+ activated ATPase of SPM of tolerant and nontolerant mice were not significantly different. The activity of synaptic vesicular Mg++-dependet ATPase was dependent on the concentration of Mg++ but not of Ca++; maximum activity was obtained with 2 mM MgCl2. On the other hand, Mg++-dependent ATPase activity of SPM was dependent on both Mg++ and Ca++, activity being maximum using 2 mM MgCl2 and 10-5 M CaCl2. It is suggested that this stimulation of ATPase activity may alter synaptic transmission and may thus be involved in some aspects of morphine tolerance and dependence.

Original languageEnglish (US)
Pages (from-to)1533-1539
Number of pages7
JournalLife Sciences
Volume20
Issue number9
DOIs
StatePublished - May 1 1977

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