In vivo effects of Pain Relieving Plaster on closed soft tissue injury in rabbit ears

BACKGROUND Soft tissue injury imposes major public health burdens worldwide. The positive effect of China's Tibetan medicine and the Lamiophlomis rotata-based herbal Pain Relieving Plaster (PRP) on healing closed soft tissue injury (CSTI) has been reported. The herbs contained in Plaster are also referred as 'blood-activating and stasis-dispelling' in herbal medicine. The formula of the plaster contains four China's Tibetan medical herbs, including Lamiophlomis rotata, Oxytropis falcate Bunge, Curcuma longa Linn, and Myricaria bracteata. Two of these herbs (Lamiophlomis rotate; Curcuma longa Linn) are commonly used in different formulae of Chinese medicine. The objective of this study is to use an interdisciplinary approach to test the hypothesis that the formula and its components influence the process of CSTI. METHODS In vivo models have been established in 30 rabbit ear pinnae and studied for: (1) blood flow velocity (BFV) which was affected by pressure of 21.2 kg/cm2 for 30 second over the local rabbit ear tissue; (2) edema formation of the closed soft tissue injury; (3) in vivo local temperature change. RESULTS The results of in vivo studies indicated that CSTI significantly increased the velocity of blood flow and increased edema formation within the control group. The PRP extracts for 5 hours significantly slowed down the BFV of CSTI in rabbit ears, markedly decreased the elevated edema level from the 3rd to the 5th day. CONCLUSION The ingredients contained in the formula have positive effects in healing CSTI and further study is worth exploring.