Tyrosine hydroxylase activation. Comparison of in vitro phosphorylation and in vivo administration of haloperidol.

摘要: Abstract Rat striatal tyrosine hydroxylase (TH) was assayed 2 hr following treatment with 1 mg/kg haloperidol. TH activity in striata from haloperidol-treated rats (haloperidol TH) increased significantly relative to control when at pH 7.0, but not 6.0, the presence of 175 μM tetrahydrobiopterin (BH4). also phosphorylated vitro, catalyzed by sufficient quantities catalytic subunit bovine heart protein kinase cause greater than 90% activation after 10 min. activated phosphorylation both 6.0 and 7.0 Haloperidol TH, phosphorylation, there no difference between haloperidol either or phosphorylation. Comparison Lineweaver-Burk plots nonphosphorylated indicated that due a 5-fold change Km for BH4 2-fold Vmax 7.0. kinetics were intermediate those Analysis Lineweaver-Burk, Hanes-Woolf, Eadie-Scatchard suggested kinetic data result mixture two forms enzyme, different affinities cofactor. Theoretical calculations mixtures could be explained postulating 25–35% molecules 35–75% nonphosphorylaed molecules. An hypothesis role during conditions neuronal firing rate, such as may occur treatment, is presented.