[Activation succinate dehydrogenation in rat liver by noradrenaline, cAMP and acute cooling]

Administration of noradrenaline in a dose of 11 mumol/kg activates succinate dehydrogenase (SDH) in the rat liver. On incubation of liver homogenate with noradrenaline (10(-6) M), cAMP (10(-6) M) and NaF (10(-2) M), a nonhormonal activator of adenylate cyclase, SDH was found to be activated by 20--30% in all the cases. The effects of noradrenaline and cAMP did not sum up. It seems likely that SDH activation by catecholamines is mediated by cAMP. Acute cooling (--17 degrees C) stimulates SDH via endogenous catecholamines, since this effect is completely reversed by the beta-adrenolytic inderal.