title: The influence of dihydroergotoxine mesylate on the low-Km phosphodiesterase of cat and rat brain in vitro.
abstract: Dihydroergotoxine mesylate (DHET; active substance of Hydergine) was shown to be a stronger inhibitor of the low-Km than of the high-Km phosphodiestrase (PE) in cat and rat brain homogenates. The inhibition due to DHET was greater when a purified low-Km PE preparation originating from a sonicated pellet (100,000 g) of rat brain tissue was used. The drug alters the kinetic properties of the enzyme, producing a lowering of the negative cooperativity effect. This kind of PE inhibition is of particular importance at normal cellular cAMP levels, but does not interfere with cAMP production by hormonal stimulation.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002415:Cats; D002540:Cerebral Cortex / Q000201:enzymology*; D004088:Dihydroergotoxine / Q000494:pharmacology*; D007700:Kinetics; D051381:Rats
chemical_list: D004088:Dihydroergotoxine; D015105:3',5'-Cyclic-AMP Phosphodiesterases