The influence of nicergoline on reaction kinetics of synaptosomal adenosine triphosphatases from porcine brain.
10-Methoxy-1,6-dimethylergoline-8beta-methanol-5-bromonicotinate (nicergoline) has in vitro a modulatory effect upon reaction kinetics of two synaptosomal adenosine triphosphatases from porcine brain: Na,K-dependent ATPase and Ca,Mg-dependent ATPase. Nicergoline is a non-competitive inhibitor of synaptosomal Ca,Mg-dependent ATPase in vitro; thus, if its in vivo concentration reaches a sufficiently high level, the rate of exchange of Ca and Mg ions between the intra- and the extracellular spaces of neurons slows down. In vivo effect of nicergoline upon reaction kinetics of synaptosomal Na,K-dependent ATPase is complex; below 80 micromol/l ATP it is an activator, and above 80 micromol/l ATP it is an inhibitor or enzyme. It decreases Km for ATP from 310 micromol/l in the absence, to 70 micromol/l in the presence of 0.3 mmol/l drug. It is believed that, in vivo, nicergoline helps to level or normalize the rate of physiological processes energetically coupled to synaptosomal Na,K-dependent ATPase, by moderately accelerating the slow and strongly inhibiting the fast reaction rates by ATP hydrolysis.
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D004873:Ergolines / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D009530:Nicergoline / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013552:Swine; D013574:Synaptosomes / Q000201:enzymology*
D004873:Ergolines; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D009530:Nicergoline