OBSERVATIONS ON BLOOD-PRESSURE RESPONSES TO INJECTIONS OF MEDICINAL PLANT-EXTRACTS IN RATS

Aqueous extracts of plant species from different families produced dos e dependent decreases in blood pressure in rat within the first minute (immediate hypotensive response) and in duration of this hypotensive response following i.v. injection, while the subsequent response could be either hypotensive or hypertensive depending on plant species. The subsequent response was not dose-related in both magnitude and durati on. The immediate hypotensive response was not due to the vehicle (NaC l solution) nor the common cations present in the extracts. It represe nted probably a reflex response with chemicals in the plant extracts a cting on the peripheral chemoreceptors, or in the pacemaker and/or car diac tissue, leading to a decrease in heart rate and tension. The subs equent hypotensive/hypertensive response was due to the chemicals acti ng on targets in different parts of various body systems.