ABSTRACT
AIM OF THE STUDY: The present study was aimed to investigate the pharmacological basis for the use of Loranthus ferrugineus in hypertension. MATERIALS AND METHODS: Loranthus ferrugineus methanol extract (LFME) was obtained using Soxhelt extractor and then successively fractionated using chloroform, ethyl acetate and n-butanol. The n-butanol fraction of LFME (NBF-LFME) was studied using isolated rat thoracic aorta. RESULTS: NBF-LFME (1.0 x 10(-5) to 3.0mg/ml) was found to be the most potent to concentration-dependently relax the endothelium-intact phenyephrine (PE, 1 microM)- and high K(+) (80 mM)-precontracted rat aortic rings. Removal of the endothelium completely abolished the vascular relaxing properties of NBF-LFME. Pretreatment with atropine (1 microM), L-NAME (10 microM), indomethacin (10 microM) and methylene blue (10 microM) significantly blocked NBF-LFME-mediated relaxation. Endothelium-dependent and -independent relaxations induced by acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were significantly enhanced in aortic rings pretreated with NBF-LFME when compared to those observed in control aortic rings. On the contrary, glibenclamide (10 microM), propranolol (1 microM) and prazosin (0.01 microM) did not alter NBF-LFME-induced relaxation. CONCLUSIONS: The results suggest that NBF-LFME induced vascular relaxation by stimulating muscarinic receptors, activating the endothelium-derived nitric oxide-cGMP-relaxant pathway, promoting prostacyclin release and/or possibly through its ability to lengthen the released nitric oxide half-life. The present data further supports previous in vivo findings and explain the traditional use of Loranthus ferrugineus as an anti-hypertensive agent.
Subject(s)
Antihypertensive Agents/pharmacology , Aorta, Thoracic/drug effects , Loranthaceae/chemistry , Plant Extracts/pharmacology , Animals , Antihypertensive Agents/antagonists & inhibitors , Antihypertensive Agents/chemistry , Antihypertensive Agents/pharmacokinetics , Antioxidants/analysis , Dose-Response Relationship, Drug , Drug Synergism , Endothelium, Vascular/drug effects , Endothelium, Vascular/physiology , Flavonoids/analysis , In Vitro Techniques , Malaysia , Male , Medicine, East Asian Traditional , Phenols/analysis , Phytotherapy , Plant Components, Aerial/chemistry , Plant Extracts/antagonists & inhibitors , Plant Extracts/chemistry , Plant Extracts/pharmacokinetics , Rats , Rats, Sprague-Dawley , Vasoconstrictor Agents/antagonists & inhibitors , Vasoconstrictor Agents/pharmacology , Vasodilation/drug effects , Vasodilator Agents/pharmacokinetics , Vasodilator Agents/pharmacologyABSTRACT
The World Health Organization (WHO) Multicentre Growth Study (MGRS) Middle East site was Muscat, Oman. A survey in Muscat found that children in households with monthly incomes of at least 800 Omani Rials and at least four years of maternal education experienced unconstrained growth. The longitudinal study sample was recruited from two hospitals that account for over 90% of the city's births; the cross-sectional sample was drawn from the national Child Health Register. Residents of all districts in Muscat within the catchment area of the two hospitals were included except Quriyat, a remote district of the governorate. Among the particular challenges of the site were relatively high refusal rates, difficulty in securing adherence to the protocol's feeding recommendations, locating children selected for the cross-sectional component of the study, and securing the cooperation of the children's fathers. These and other challenges were overcome through specific team building and public relations activities that permitted the successful implementation of the MGRS protocol.
