Arachidonate activates muscle electrogenic sodium pump and brain microsome Na+,K+-ATPase under suboptimal conditions.
Arachidonate 5 x 10(-5) mol.l-1 increased the rate of hyperpolarization induced in Na+-loaded mouse diaphragm fibers by 5 mmol.l-1 K+. When applied to Na+-loaded muscles without potassium, arachidonate 1 x 10(-6) and 5 x 10(-5) mol.l-1 induced a ouabain-sensitive hyperpolarization of the muscle fibers. The activity of rat brain microsomal Na+,K+-ATPase was stimulated by 1 x 10(-7)-5 x 10(-6) mol.l-1 arachidonate in reaction media with reduced amounts of ATP or K+ and after short-lasting sonication of the samples. It was concluded that, under particular conditions, arachidonate might serve as a Na+,K+-ATPase activator or inhibitor regulating its ion transport and electrogenicity.
Vyskocil
F
F
Institute of Physiology, Czechoslovak Academy of Sciences, Praha.
Zemková
H
H
Teisinger
J
J
Svoboda
P
P
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D003964:Diaphragm / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004594:Electrophysiology; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D001095:Arachidonic Acids; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium