The effect of papaverine on sodium-potassium adenosine triphosphatase and the ouabain sensitive electrical properties of crayfish nerve
| Autor: | Edward M. Lieberman, W.T. Woods |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
Epinephrine
ATPase Astacoidea Ouabain Membrane Potentials chemistry.chemical_compound Norepinephrine Papaverine medicine Cyclic AMP Animals Cyclic adenosine monophosphate Cyclic GMP Membrane potential Adenosine Triphosphatases Neurons biology General Neuroscience Sodium Giant axon Temperature Phosphodiesterase Lysophosphatidylcholines Adenosine Monophosphate Kinetics chemistry Biochemistry Xanthines biology.protein Biophysics Acetylcholinesterase Potassium Triphosphatase medicine.drug |
| Zdroj: | Neuroscience. 1(5) |
| ISSN: | 0306-4522 |
| Popis: | The effect of cyclic and non-cyclic nucleotides and phosphodiesterase inhibitors on (Na-K)-adenosine triphosphatase (ATPase) activity of crayfish nerve membrane fragments and on the ouabain sensitive electrical properties of the intact crayfish giant axon was investigated. Only papaverine (1 × 10 −7 −2 × 10 −4 m ), of the phosphodiesterase inhibitors stimulated the adenosine triphosphatase to approximately 2.5 times its control level. The methylxanthine inhibitors (caffeine and aminophylline) had no effect. The papaverine induced stimulation did not alter substrate or ionic activation kinetics or the ouabain sensitivity of the ATPase activity. Cyclic and non-cyclic nucleotides, slightly but significantly inhibited the (Na-K)-adenosine triphosphatase if the membrane preparation was preincubated with these agents prior to activation of enzyme activity. Addition of 3 m m adenosine triphosphate to the incubation medium simultaneous with test nucleotides prevented the inhibition. Addition of the phosphodiesterase inhibitors in conjunction with the nucleotides had no effect on adenosine triphosphatase activity other than that accounted for by the nucleotides alone. Papaverine (1−10 × 10 −6 m ) increased the membrane resistance and the temperature dependence of the membrane potential of the intact axon. The action of papaverine was totally prevented if the axon was pretreated with 0.5–1 m m ouabain. The papaverine stimulated axon was more sensitive to ouabain inhibition than the untreated control axon. The results suggest (a) papaverine acts to stimulate the (Na-K)-adenosine triphosphatase of the membrane fragments and the ouabain sensitive electrogenic transport properties of the intact axon and, (b) papaverine does not appear to act through a cyclic adenosine monophosphate mediated mechanism to stimulate the (Na-K)-adenosine triphosphatase. |
| Databáze: | OpenAIRE |
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