[Effects of ifenprodil on the adenosine triphosphatase of guinea pig liver mitochondria].
The effects of ifenprodil on adenosine triphosphatase (ATPase) activity were examined using guinea pig liver mitochondria. 1) Intact mitochondrial ATPase activity was stimulated by ifenprodil in a concentration-dependent manner, this effect being further potentiated with dinitrophenol. The stimulation by ifenprodil appeared with only ATP among four nucleotides as substrate. Mg2+ and Ca2+ attenuated the effect of ifenprodil. Ifenprodil abolished the KCN-induced inhibition. 2) Heat-treated mitochondrial ATPase activity, kept for 60 min at 50 degrees C, was decreased in a concentration-dependent manner by ifenprodil. The inhibitory effect of ifenprodil was abolished by Mg2+ and Ca2+. These results indicate that ifenprodil has two behaviors, acceleration of a latent ATPase and inhibition of an activated ATPase. These findings, together with our previous data, suggest that ifenprodil seems to affect the actions of Mg2+ and Ca2+ on mitochondrial ATPase by directly affecting the membrane, and these mechanisms may be involved in its anti-cyanide effect.
Department of Biochemistry, Faculty of Pharmaceutical Science, Kinki University, Osaka, Japan.
Y
Y
Yamashita
Y
Y
Miyake
S
S
Mitsuhiro
T
T
Furukawa
D000251:Adenosine Triphosphatases / Q000032:analysis*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D004140:Dinitrophenols / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006358:Hot Temperature; D066298:In Vitro Techniques; D008274:Magnesium / Q000008:administration & dosage; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D010880:Piperidines / Q000494:pharmacology*; D011188:Potassium / Q000008:administration & dosage; D012964:Sodium / Q000008:administration & dosage; D014665:Vasodilator Agents / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D004140:Dinitrophenols; D010880:Piperidines; D014665:Vasodilator Agents; D012964:Sodium; D000251:Adenosine Triphosphatases; D008274:Magnesium; C010739:ifenprodil; D011188:Potassium