Ethylmalonic acid inhibits mitochondrial creatine kinase activity from cerebral cortex of young rats in vitro.
Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is an inherited metabolic disorder biochemically characterized by tissue accumulation of predominantly ethylmalonic acid (EMA) and clinically by neurological dysfunction. In the present study we investigated the in vitro effects of EMA on the activity of the mitochondrial (Mi-CK) and cytosolic (Cy-CK) creatine kinase isoforms from cerebral cortex, skeletal muscle, and cardiac muscle of young rats. CK activities were measured in the mitochondrial and cytosolic fractions prepared from whole-tissue homogenates of 30-day-old Wistar rats. The acid was added to the incubation medium at concentrations ranging from 0.5 to 2.5 mM. EMA had no effect on Cy-CK activity, but significantly inhibited the activity of Mi-CK at 1.0 mM and higher concentrations in the brain. In contrast, both Mi-CK and Cy-CK from skeletal muscle and cardiac muscle were not affected by the metabolite. We also evaluated the effect of the antioxidants glutathione (GSH), ascorbic acid, and alpha-tocopherol and the nitric oxide synthase inhibitor L-NAME on the inhibitory action of EMA on cerebral cortex Mi-CK activity. We observed that the drugs did not modify Mi-CK activity per se, but GSH and ascorbic acid prevented the inhibitory effect of EMA when co-incubated with the acid. In contrast, L-NAME and alpha-tocopherol could not revert the inhibition provoked by EMA on Mi-CK activity. Considering the importance of CK for brain energy homeostasis, it is proposed that the inhibition of Mi-CK activity may be associated to the neurological symptoms characteristic of SCAD deficiency.
Leipnitz
Guilhian
G
Laboratório de Erros Inatos do Metabolismo, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, RS, Brazil.
Schuck
Patrícia F
PF
Ribeiro
César A J
CA
Dalcin
Karina B
KB
Assis
Dênis R
DR
Barschak
Alethea G
AG
Pulrolnik
Vânia
V
Wannmacher
Clóvis M D
CM
Wyse
Angela T S
AT
Wajner
Moacir
M
D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D003402:Creatine Kinase / Q000037:antagonists & inhibitors*; D003600:Cytosol / Q000201:enzymology; D008314:Malonates / Q000494:pharmacology*; D008928:Mitochondria / Q000201:enzymology*; D008929:Mitochondria, Heart / Q000201:enzymology; D008931:Mitochondria, Muscle / Q000201:enzymology; D018482:Muscle, Skeletal / Q000201:enzymology; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar
D008314:Malonates; C038080:ethylmalonic acid; D003402:Creatine Kinase