PT  - JOURNAL ARTICLE
AU  - D Desaiah
AU  - I K Ho
TI  - Effects of acute and continuous morphine administration on catecholamine-sensitive adenosine triphosphatase in mouse brain.
DP  - 1979 Jan 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 80--85
VI  - 208
IP  - 1
4099  - http://jpet.aspetjournals.org/content/208/1/80.short
4100  - http://jpet.aspetjournals.org/content/208/1/80.full
SO  - J Pharmacol Exp Ther1979 Jan 01; 208
AB  - The catecholamine-stimulated adenosine triphosphatase (ATP-ase) activities in mouse brain synaptosomes were inhibited by morphine both in vitro and in vivo. Morphine up to 10(-3) M had no effect on basal ATPase activities but at 10(-4) M significantly inhibited dopamine-sensitive ATPase activities in vitro. The morphine effect was antagonized by an opiate antagonist, naloxone. The catecholamine-sensitive ATPase activities were also inhibited by acute administration of morphine. The inhibition was dose-dependent. However, naloxone partially antagonized the morphine inhibition of depamine-sensitive ATPase activity but not norepinephrine-sensitive ATPase activity. A significant decrease in the sensitivity of synaptosomal ATPase to catecholamines was observed in mice rendered tolerant by morphine pellet implantation. The Na+,K+-ATPase was more affected by morphine as compared to Mg++-ATPase activity. The dopamine-sensitive Na+,K+-ATPase activity was restored by 50% in precipitated withdrawal mouse brain synaptosomes. Norepinephrine-sensitive ATPase activity was also restored partially in precipitated withdrawal animals. These results suggest that in mouse brain synaptosomes morphine may be interacting with ATPase at or near the catecholamine-active sites.