Effects of noradrenaline on the activation and the stability of brain adenylate cyclase.
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 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 preincubation of particle preparations of brain cortex at 38 degrees 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.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002540:Cerebral Cortex / Q000201:enzymology; D003342:Corpus Striatum / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D013696:Temperature
D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D000262:Adenylyl Cyclases; D008274:Magnesium; D009638:Norepinephrine