Oscillating contractions in protoplasmic strands of Physarum: effects of externally applied ouabain, sodium-, potassium- and calcium-ions.
1. Concentrations of 0.1-10 mM Ouabain do not affect oscillating contractions, when applied externally in physiological solutions. 2. Ouabain has no effect, when applied in solutions of increased sodium- (100 mM) and lowered potassium-concentration (0.1 or zero mM). 3. De novo generation of oscillating contractions in protoplasmic drops is not suppressed in Ouabain-solutions. 4. Biochemical studies of Na-K-ATPase did not show any Ouabain sensitive ATPase-activity. 5. Reaction of veins on high concentrations (300 mosm) is discussed as to be a physical effect. 6. It is concluded that no Na-K-ATPase is engaged in triggering oscillating contraction automaticity.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D003593:Cytoplasm / Q000187:drug effects / Q000502:physiology; D003595:Cytoplasmic Streaming / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology*; D010804:Physarum / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D002110:Caffeine; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium