PHENYLARSINE OXIDE STIMULATES PYRIDINE NUCLEOTIDE-LINKED CA2-LIVER MITOCHONDRIA( RELEASE FROM RAT)

Rat liver mitochondria contain a specific Ca2+ release pathway which o perates when oxidized mitochondrial pyridine nucleotides are hydrolyse d to ADPribose and nicotinamide. Here we report that the hydrophobic b ifunctional thiol reagent phenylarsine oxide (PhAsO) at low concentrat ions stimulates this pathway by promoting a Ca2+-dependent hydrolysis of oxidized mitochondrial pyridine nucleotides. Ca2+ release is inhibi ted by cyclosporine A or m-iodobenzylguanidine, compounds known to pre vent intramitochondrial pyridine nucleotide hydrolysis or protein mono (ADPribosyl)ation, respectively. At higher concentrations, PhAsO cause s non-specific leakiness of mitochondria.