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Folium cum Flore Crataegi
arrhythmias, hypotensive crisis and mortality (56, 57). The oligomeric
procyanidin-enriched fraction did not decrease the reperfusion-induced
elevation of creatine kinase plasma levels (57). Administration of powdered
leaves and flowers to rats (2% of diet) reduced the release of lactate
dehydrogenase after perfusion-induced heart ischaemia (58).
Effect on coronary blood flow
Intragastric administration of an oligomeric procyanidin fraction of a
standardized leaf and flower extract to dogs at a dose of 12–70 mg/kg
body weight, three times daily for 60 days, increased myocardial blood
flow (59, 60). Intravenous injection of an aqueous or 95% ethanol extract
of the flowers increased coronary blood flow and cardiac output, and decreased
peripheral resistance in both dogs and guinea-pigs (61–63). Administration
of a flavonoid-enriched extract to cats and rabbits increased
coronary blood flow by 48% and 163%, respectively, and reduced pituitrin-induced
coronary insufficiency in rabbits (52). Intravenous administration
of a leaf with flower extract to cats (10 mg/kg body weight) or
rabbits (20 mg/kg body weight) dilated coronary blood vessels, and improved
coronary blood flow (53).
Effect on action potential
A leaf preparation (10 mg/l) prolonged the duration of the action potential
and delayed the recovery of V max
in isolated guinea-pig papillary muscle
(42). The electrophysiological correlation between the increase in the
contraction amplitude of isolated canine papillary muscles, and vasodilation
in isolated human coronary arteries, was measured after application
of an extract of the leaves with flowers. The cardiac action potential significantly
increased in duration and overshoot, and maximal depolarization
(P < 0.001). Hyperpolarization of the resting membrane of normal
and arteriosclerotic vascular smooth muscle cells of the human coronary
artery was observed after treatment with flavonoids isolated from the extract
(0.1 and 100 µmol/l). The isometric wall tension decreased in both
normal and arteriosclerotic vessels. The increase of peak-to-plateau repolarization
in cardiac action potential and hyperpolarization of vascular
smooth muscle suggest that the extract acts as a potassium channel agonist
(64, 65).
Antihypertensive effects
In various animal models, a decrease in peripheral vascular resistance and
hypertension occurred after treatment with leaf and/or flower extracts (50,
54, 66–69). Intravenous administration of a standardized fluidextract of the
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