Abstract
The effects of 50% Drink of Myrica rubra (MRD) on the cardiovascular system of the rat and on the platelets aggregation of
rats and guinea pigs were studied.
Method:
Different groups of male Wistar rats were treated either with 50% Myrica rubra drink as drinking vehicle (4 weeks) or water. The animals were then prepared for
the measurement of arterial blood pressure and heart rate, ECG, sensitivity of the
baroreceptors, platelets’ aggregation, blood clotting time and cardiac parasympathetic
ganglia. The mechanism of action of any induced effect was elucidated using different
receptor blockers.
Results:
Treatment induced a significant decrease in the arterial blood pressure and heart
rate on Wistar rats, but no significant changes in the ECG were observed. Pretreatment
of rats with MRD 10 or 20 ml/kg (i. p.) significantly suppressed vagal electrical
stimulation to the heart and nicotine-induced bradycardia, via decreasing phenylephrine-induced
rise in the arterial blood pressure and the reflexly-induced bradycardia. It significantly
suppressed the Baroreceptor Sensitivity Index (BSI). The treatment also significantly
suppressed ADP-induced platelets aggregation in rats and arachidonic acid-induced
aggregation in guinea pigs.
Discussion:
All these actions seemed to be mediated by the MRD constituents such as proanthocyanidins,
polyphenols and flavonoids. The decreases in the heart rate and BSI were probably
caused by an inherent ability to block the parasympathetic ganglia.
Conclusion:
The results of this study regarding the effects of MRD actions on the cardiovascular
system and platelets qualify the drink to be classified as a functional food.
Key words
drink of Myrica rubra - experimental animals - arterial blood pressure - heart rate
- coagulation