INHIBITORY EFFECT OF VANADATE ON PROTEIN PHOSPHATASE, GLYCOGEN-PHOSPHORYLASE AND PROTEIN-KINASE IN EXTRACTS FROM SEVERAL RAT-TISSUES

The purpose of this study was to determine the in vitro effect of incr easing vanadate concentrations (1 nM-1 mM) on protein phosphatase (PP) and glycogen phosphorylase (GP) of extracts from several rat tissues. PP activity was inhibited in various brain structures by moderate con centrations of vanadate: however, in the spinal cord, comparatively lo w concentrations (10 nM) of vanadate caused a steep increase in enzyme activity. Only at a high concentration (1 mM) did vanadate produce mo derate PP inhibition. Reciprocal correlation was obtained between vana date effects on PP and GP in various parts of the nervous system. In t he last series of experiments the effect of vanadate upon protein kina se (PK) activity in various regions of the CNS was determined; low and intermediate vanadate concentrations produced a moderate activation; higher vanadate concentrations suppressed the enzyme activity. Vanadat e at a concentration of 0.1 mM produced activation of PK in the medull a oblongata, whereas at mM vanadate there was significant inhibition o f PK. The spinal cord enzyme was more sensitive to vanadate, being inh ibited at concentrations of 10 nM-1 mM. (C) 1997 Published by Elsevier Science Ltd.