Carrageenan-Induced Paw Edema

The method described by Ayal²⁹ was followed with minor modification to study the effect of solvent fractions of 80% methanol leaf extract of A. aspera on acute inflammation. Rats fasted overnight with free access to water until the experiment commenced. The basal volume, ie displacement of water by the left hind paw of each rat, was determined using a calibrated plethysmometer and randomly assigned to their respective groups before administration of the substance as described in Grouping and Dosing of Animals. Then, the rats were treated with test substances by making use of oral gavage. After 1 hr of test administration, inflammation was induced in the left hind paw by injecting 0.05 mL of freshly prepared 1% carrageenan suspension in normal saline into the sub-plantar surface of the left hind paw. The change in volume of the injected paw was measured after 1, 2, 3 and 4 hrs post-induction with carrageenan using a plethysmometer.²⁸

PEC = paw edema of negative control and PET = paw edema of test groups, including the standard.