Invited Symposium: Medicinal Plants and Drug Actions
Zhang, CY (Department of Pharmacology, National University of Singapore, Singapore)
Two constituent diterpenoid lactones from the tropical shrub, Andrographis paniculata, 14-deoxyandrographolide (DA) and 14-deoxy-11,12-didehydroandrographolide (DDA), were used in anaesthetised rats, isolated rat thoracic aortae and atria and endothelial cell culture to examine their effects on cardiovascular-related parameters. DA and DDA were found to decrease significantly the mean arterial pressure and heart rate of anaesthetised normotensive rats. Both DA and DDA caused relaxation of the isolated rat thoracic aortae through activation of the nitric oxide (NO) synthase and guanylyl cyclase pathways, as well as the blockade of Ca2+ influx via voltage- and receptor-operated Ca2+ channels. DA and DDA also stimulated NO production in endothelial cells. DDA appeared to be more potent than DA in its vasorelaxant and NO stimulant effects. It was further demonstrated that the hypotensive effect of DDA was mediated through the autonomic ganglion and -adrenoceptors, as well as ACE inhibition.
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|Tan, BKH; Zhang, CY; (1998). Pharmacological Mechanisms of Cardiovascular Actions of Diterpenoids of Andrographis Paniculata. Presented at INABIS '98 - 5th Internet World Congress on Biomedical Sciences at McMaster University, Canada, Dec 7-16th. Invited Symposium. Available at URL http://www.mcmaster.ca/inabis98/kwan/tan0674/index.html|
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