Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
 ...
PMID:Effects of acute and continuous morphine administration on catecholamine-sensitive adenosine triphosphatase in mouse brain. 21 49

Effects of K+, ethanol and norepinephrine on the binding kinetics of ouabain to (Na+,K+)-adenosine triphosphatase in beef brain microsomes were examined. K+ reduced the rate and apparent affinity for ouabain binding markedly. Whereas ethanol and norepinephrine themselves inhibited ouabain binding slightly, they stimulated binding in the presence of K+. Norepinephrine enhanced the effect of ethanol. Dissociation of ouabain was biphasic, with fast and slow components corresponding to high and low apparent affinity. About 65% of the enzyme had high affinity, regardless of conditions. Norepinephrine and ethanol had differential effects on the rate of dissociation from high and low affinity enzyme, however. Alpha receptor blockade generally prevented the effects of norepinephrine. These results show that, although norepinephrine and ethanol have a modest effect on the amount of enzyme that can bind ouabain, their main effect on (Na+,K+)-adenosine triphosphatase is to antagonize the binding of K+ to its allosteric site that inhibits ouabain binding. The data support the hypothesis that ouabain binds rapidly to a K+-insensitive form of phosphorylenzyme or to its dephosphorylated analog and dissociates rapidly from E1.
 ...
PMID:Ouabain binding to brain (Na+,K+)-adenosine triphosphatase: interactions of K+, ethanol and norepinephrine with high- and low-affinity binding. 302 3