The effects of Heteromorpha trifoliata root bark aqueous extract on rat blood pressure

The aqueous extract of H. trifoliata root bark lowers blood pressure in the anaesthetized rat. This depressor response is not antagonized by atropine nor diphenhydramine, indicating that muscarinic and histaminic (H1) receptors are not involved. However, as it is abolished by propranolol, the stimulation of beta 2 receptors on skeletal muscle blood vessels may be involved.