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 beverage drinks in southern China. In fact, various Ilex species have been used in Chinese folk medicine to treat coronary heart diseases. The mode of action is believed to be mediated by their coronary vasodilative effects. In this study, the water extract of the leaves of Ilex latifolia (IK-TP) was shown 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 purified enzyme from porcine cerebral cortex. IK-TP also inhibited Ca2+-dependent 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 suggests the presence of ATPase inhibitory compounds in Ilex latifolia with specificities different from that of ouabain.