Effects of an Extract of Hawthorn on Arterial Blood Pressure in Anaesthetized Rats
Susan WS*, Miranda MW Wong and Ricky YK Man
Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P.R. China
- *Corresponding Author:
- Susan WS Leung
Department of Pharmacology and Pharmacy
2/F Laboratory Block, Faculty of Medicine Building
21 Sassoon Road, Pokfulam, Hong Kong SAR, China
E-mail: [email protected]
Received date: January 14, 2013; Accepted date: January 28, 2013; Published date: January 30, 2013
Citation: Leung SWS, Wong MMW, Man RYK (2013) Effects of an Extract of Hawthorn on Arterial Blood Pressure in Anaesthetized Rats. Cardiol Pharmacol 2:104. doi: 10.4172/2329-6607.1000104
Copyright: © 2013 Susan WS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Hawthorn is an herbal medicine that has been used to treat various cardiovascular disorders, including angina, arrhythmias, congestive heart failure and hypertension. Its major components include flavonoids and oligomeric procyanidins. The present study examined the cardiovascular effects of a commercial available hawthorn extract (WS 1442) in anaesthetized rats. Male adult Sprague Dawley rats were anaesthetized and their carotid arteries were cannulated for blood pressure and heart rate measurement. After bolus intravenous injections of WS 1442 (3.125, 6.25, 12.5 and 25 mg.kg-1), mean arterial blood pressure (104 ± 3 mmHg) was reduced transiently in a dose-dependent manner. A greater effect on the diastolic than on the systolic blood pressure was observed. Heart rate was not significantly affected by all doses of WS 1442. Infusion of WS 1442 (10 and 28 mg.kg-1.min-1 for 7 min) resulted in sustained decreases in mean arterial blood pressure without any significant changes in heart rate.
wenty minutes after the infusion, mean arterial blood pressure returned to the baseline values. Phenylephrine (1, 3 and 10 μg.kg-1) dose-dependently increased arterial blood pressure and this hypertensive effect in rats with prior exposure to WS 1442 was significantly smaller than in those without. These findings suggest that the hawthorn extract possesses hypotensive action. Pre-exposure to the hawthorn extract also impaired the blood pressure response to phenylephrine. As such, hawthorn may have a modulatory effect on the regulation of blood pressure by a-adrenergic system.