Noradrenergic stimulation increases (Na+, K+)-adenosine triphosphatase activity (original) (raw)
Related papers
A simple method for the purification of rat brain Na+,K+-adenosine triphosphatase (ATPase)
Journal of pharmacological methods, 1982
Several methods of purification of Na+,K+-adenosine triphosphatase (ATPase) have been previously described for a wide variety of tissues. In general, highest activity preparations have necessitated large amounts of tissue and many purification steps. This article describes a technique that allows partial purification of Na+,K+-ATPase from as few as 15 rat brains and should be of interest to investigators of the pharmacology of this particular enzyme system. In this modified version of the Jorgensen procedure (Biochim Biophys Acta 356:36--52, 1974) we purified the Na+,K+-ATPase from 15--90 rat brains, and obtained enzyme preparations with a mean specific activity of 552 +/- 37.6 mumol Pi/mg of protein/hr (95.5% ouabain sensitive). This "purified" enzyme had an activity ratio (Mg2+ + Na+ + K+)/(Mg2+ + Na+) of 47.4 +/- 12.3 SEM, compared to 3.29 +/- 0.17 SEM for the untreated microsomes. Ouabain inhibited the "purified" enzyme with an I50 of 6 X 10(-9) M. Ouabain bi...
Noradrenaline and thyroid function regulate (Na+,K+)-adenosine triphosphatase independently in vivo
European Journal of Pharmacology, 1989
We investigated interactions between noradrenaline and thyroid hormone status in the regulation of (Na+,K+) -ATPase in vivo. Treatment with the fl-adrenoceptor antagonist propranolol or with the neurotoxin 6-hydroxydopamine did not prevent the increases in heart (Na+,K +)-ATPase associated with triiodothyronine treatment. Administration of methimazole did not prevent the increase in (Na+,K +)-ATPase indices in cerebral cortex and heart associated with subacute noradrenergic stimulation by yohimbine. There was no evidence for synergistic effects between thyroid hormone administration and noradrenergic stimulation by yohimbine. Thyroid hormone, unlike noradrenaline, mainly increased (Na+,K+)-ATPase activity with low affinity for ouabain. These results show that noradrenaline and thyroid hormone regulate (Na+,K +)-ATPase by largely independent mechanisms, and may regulate different populations of enzyme molecules. Thyroid hormone; (Na+,K+)-ATPase; Noradrenaline (metabolic effects); Ouabain binding; 6-Hydroxydopamine
Adenosine triphosphatase activity in glial cells and in neuronal perikarya of edematous rat brain
Brain Research, 1974
The activity of Na,K-ATPase and the ouabain insensitive ATP-hydrolyzing activity was studied in fractions of glial cells and of neuronal perikarya isolated in bulk from cortex and subcortical white matter of rats, previously treated with intraperitoneal administration of water. With increasing water load, the cortical Na,K-ATPase activity markedly decreased in glial cells and was slightly elevated in neuronal perikarya of edematous brain. The Na,K-ATPase of the glial cells and of the neuronal perikarya of white matter, on the other hand, exhibited no significant changes in specific activity. The ouabain-insensitive ATPase activity behaved similarly. It was markedly decreased in cortical glial cells isolated from rats receiving water equaling 20 70 or 30 70 of their body weight, respectively, whereas no change of the cortical ouabain-insensitive ATPase was observed in the neuronal perikarya.
Biochimica Et Biophysica Acta (bba) - Biophysics Including Photosynthesis, 1966
The kinetics of the hydrolysis of ATP by a rat-brain lipoprotein fraction have been investigated. The activity is greatly increased in the presence of Na + and K +, but reaches a maximum value and then suffers a diminution in the presence of an excess of either ion. Kinetic evidence indicates that these ions combine with the enzyme protein according to Michaelis-Menten kinetics, that 2 Na + are involved in the activation, and that the interaction of Na + and K + at each site is of a competitive nature. Inhibition of the (Na+-K+)-stimulated ATPase by ouabain, appears to result from a competition between ouabain and both K + and Na + while addition of oligomycin leads to kinetics which suggest competition of oligomycin with Na +. NH4+ may substitute for K + and, when present in excess, may also give rise to inhibitory effects.
Journal of Neurochemistry, 1975
In guinea-pig cerebral cortical slices levels of cyclic AMP increase in response to adenosine to about 200pmol/mg protein within 10min and stay at that level up to 30min. In the absence-of calcium ions and the presence of ImM-EGTA in the Krebs-Ringer-bicarbonate medium the effect of adenosine is enhanced, cyclic AMP levels rise to about 600pmol/mg protein within 30min. In normal and calcium deficient media restimulation of cyclic AMP formation with adenosine is possible after a prior stimulation with adenosine. When slices are preincubated for various periods of time with histamine or adenosine before addition of the complementary agent i.e. adenosine or histamine cyclic AMP levels obtained are unaltered compared to levels seen when adenosine and histamine are added together. Slices which are rendered unresponsive to stimulation with histamine + noradrenaline by a prior incubation with these agents do not regain any response during a 100min period of incubation in medium. The PDE inhibitors diazepam, SQ 66007 and isobutylmethylxanthine are capable of restoring the sensitivity of the slices to histamine + noradrenaline. This suggests an involvement of PDE in the unresponsive phase of the slices. Addition of adenosine to slices not affected by histamine + noradrenaline does reestablish the response of these slices to the neurohormones. A dose-response curve of adenosine for the interaction with histamine + noradrenaline yields an ED,, of 16 p~ using sensitive or desensitized slices. An adenosine concentration of only 7 PM is necessary to restore the original increase of cyclic AMP in response to histamine + noradrenaline to slices insensitive to the biogenic amines. The data are discussed in terms of a possible activation of PDE within cerebral cortical slices from guinea-pig. Adenosine may reverse this activation. The possibility of inactivation of adenylate cyclase during stimulation of cyclic AMP formation and the role of adenosine and PDE inhibitors in this process is being considered.
Biochemical Pharmacology, 1974
Adenosine 3',5'-monophosphate levels were measured in beds of incubated synaptosomes from rat cerebral cortex and found to be 15-17 pmoles/mg protein (insoluble protein after ethanol extraction) or 9-13 pmolesimg protein (TCA precipitated). Periods of incubation up to 60 mm did not cause a change in these levels. Depolarizing agents such as electrical pulses and elevated medium K' and a physiologically active compound, noradrenaline,whichdidproducelargeincreasesin theadenosine3',5'-monophosphateofratcere-bra1 cortex slices did not alter the adenosine 3',5'-monophosphate levels above those of control synaptosome beds. Histamine, which was also without effect on adenosine 3',5'-monophosphate level% caused a small but significant increase in the glutamate, GABA and aspartate released to the medium, which was qualitatively similar to the larger effect produced by electrical and K' stimulation. The small amount of adenosine 3',5'-monophosphate lost to the medium during incubation (< 10 per cent) was not altered in response to 835
Noradrenaline and thyroid function regulate (Na+,K+)-adenosine triphosphate independently in vivo
European Journal of Pharmacology, 1989
We investigated interactions between noradrenaline and thyroid hormone status in the regulation of (Na+,K+) -ATPase in vivo. Treatment with the fl-adrenoceptor antagonist propranolol or with the neurotoxin 6-hydroxydopamine did not prevent the increases in heart (Na+,K +)-ATPase associated with triiodothyronine treatment. Administration of methimazole did not prevent the increase in (Na+,K +)-ATPase indices in cerebral cortex and heart associated with subacute noradrenergic stimulation by yohimbine. There was no evidence for synergistic effects between thyroid hormone administration and noradrenergic stimulation by yohimbine. Thyroid hormone, unlike noradrenaline, mainly increased (Na+,K+)-ATPase activity with low affinity for ouabain. These results show that noradrenaline and thyroid hormone regulate (Na+,K +)-ATPase by largely independent mechanisms, and may regulate different populations of enzyme molecules. Thyroid hormone; (Na+,K+)-ATPase; Noradrenaline (metabolic effects); Ouabain binding; 6-Hydroxydopamine
Biochimica et Biophysica Acta (BBA) - General Subjects, 1966
I. p-Nitrophenylphosphatase activity was detected in a highly specific Na +and K+-dependent ATPase preparation obtained by NaI treatment of rabbit-brain microsomes. 2. The p-nitrophenylphosphatase activity required K + and was inhibited by Na +. The concentrations of K + and Na + required for half maximal activation and half maximal inhibition were 3.2 and 32 mM, respectively. 3. The p-nitrophenylphosphatase activity was inhibited by ouabain, and this inhibition was not affected by Na +. The concentration of ouabain required for 50 % inhibition of p-nitrophenylphosphatase activity was approx. 2.5" lO-5 M, which was 3 ° times that required for 5 o % inhibition of ATPase activity. However, the former was decreased to 2.5" IO-~ M by the addition of 4 ° ~M of ATP. 4. In the absence of Na + the preparation was active exclusively with p-nitrophenylphosphate. None of the following was hydrolyzed: ATP, AMP, 2'-(3')-AMP, CMP, IMP, GMP, glucose 6-phosphate, glucose 1-phosphate, /~-glycerophosphate or phenylphosphate. 5. The p-nitrophenylphosphatase activity was inhibited by a low concentration of ATP. Inhibition was of the simple non-competitive type with a K, value of 4" IO-S M. The inhibition of ATPase activity by p-nitrophenylphosphate was also of the noncompetitive type, the K, for p-nitrophenylphosphate being 4" IO-~ M. 6. The Km for p-nitrophenylphosphate was 1.5.Io-3 M, and that for ATP, 6' 10-5 M. 7. p-Nitrophenylphosphatase activity was inhibited by 60-80% with 3 mM of any of the following: GTP, UTP, CTP, ADP, AMP, PPt, or PI. 8. ATPase and p-nitrophenylphosphatase were similarly inactivated by either thermal denaturation or trypsin treatment. 9. There was a fairly good correlation between the inhibition curves for p-nitrophenylphosphatase and ATPase in the presence of increasing concentrations of N-ethylmaleimide or diisopropylphosphorofluoridate (DFP). The inhibition of both activities by DFP was markedly enhanced by K +, and the activities were protected against the inhibition by either p-nitrophenylphosphate or ATP. Io. It is suggested that the two activities could be attributed to at least two different active sites which, however, appear to be closely correlated.