Inotropic and chronotropic actions of Ilex latifolia - Inhibition of adenosine-5 '-triphosphatases as a possible mechanism

Ilex latifolia is widely used as an ingredient to prepare traditional bever age drinks in southern China. In fact, various Ilex species have been used in Chinese folk medicine to treat coronary heart diseases. The mode of acti on is believed to be mediated by their coronary vasodilative effects. In th is study, the water extract of the leaves of Ilex latifolia (IK-TP) was sho wn to increase the contractility and decrease the frequency of contraction in an isolated rat heart perfusion system. IK-TP was found to inhibit Na+/K +-ATPase activities in rat heart sarcolemma, rat brain microsomes and a pur ified enzyme from porcine cerebral cortex. IK-TP also inhibited Ca2+-depend ent ATPase at a similar dose. Following exposure of the isolated rat heart to IK-TP at a dose that produces pronounced cardiac effects, inhibition of Na+/K+-ATPase activity can be readily detected in the heart. This study sug gests the presence of ATPase inhibitory compounds ire Ilex latifolia with s pecificities different from that of ouabain. (C) 2001 Elsevier Science Inc. All rights reserved.