Effects
of noradrenaline on the activation and the stability of brain
adenylate cyclase
Brydon-Golz, S., Ohanian, H. and Bennun, A.
At constant 1 mM-ATP, the Mg2+-saturation curves for adenylate
cyclase (EC 4.6.1.1) particulate preparations obtained from
corpus striatum and cortex tissues of rat brain show that
addition of 0.1 mM-noradrenaline increases the apparent Vmax
for Mg2+by 300 % in corpus striatum particles, and by 280
% in cortex particles. At 10 mM-MgCl2, the addition of 0.1
mM-noradrenaline increased by 800 % the adenylate cyclase
activity of corpus striatum particles. At all Mg2+ concentrations,
the addition of 0.3 mM-CaCl2 suppressed the noradrenaline-induced
stimulation of adenylate cyclase of corpus striatum particles,
and even resulted in a strong inhibition of the activating
effect of Mg2+ itself on adenylate cyclase activity of cortex
particles. The addition of noradrenaline during a 3 h preincu¬bation
of particle preparations of brain cortex at 38°C decreased
by more than 4-fold the half-life of the decay of adenylate
cyclase activity. The addition of MgATP protected against
noradrenaline-induced inactivation.
Biochem. J., 166, (1977), 473-483
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