Ascorbic acid reduces Ropivacaine-induced myotoxicity in cultured human osteoporotic skeletal muscle cells.

BACKGROUND: Osteoporosis is a worldwide health issue. Loss of bone mass is a potential risk factor for fragility fractures, and osteoporotic fractures place a considerable burden on society. Bone and muscle represent a functional unit in which the two tissues are intimately interconnected. Ropivacaine is a potent local anesthetic used in clinical practice for intraoperative anesthesia and postoperative pain management, in particular for hip surgery. When injected, Ropivacaine can diffuse locally through, in particular in surrounding skeletal muscle tissue, causing dose-dependent cytotoxicity, oxidative stress and myogenesis impairment. Based on those evidences, we focused our attention on Ropivacaine-induced cytotoxicity on cultured human myoblasts. METHODS: Primary human myoblasts and myotubes from healthy subjects, osteoarthritic and osteoporotic patients (OP) were cultured in the presence of Ropivacaine. In some experiments, ascorbic acid (AsA) was added as a potent antioxidant agent. Cell viability and ROS levels were evaluated to investigate the myotoxic activity and Real-Time PCR and Western blot analysis carried out to investigate the expression of proliferation and myogenic markers. RESULTS: A dose-dependent decrease of cell viability was observed after Ropivacaine exposure in both OP myoblasts and myotubes cultures, whereas those effects were not observed in the presence of Propofol, a general anesthetic. The adding of AsA reduced Ropivacaine negative effects in OP myoblast cultures. In addition, Ropivacaine exposure also increased ROS levels and upregulated Nox4 expression, an enzyme primarily implicated in skeletal muscle ROS generation. AsA treatment counteracted the oxidant activity of Ropivacaine and partially restored the basal condition in cultures. Positive myogenic markers, such as MyoD and Myf5, were downregulated by Ropivacaine exposure, whereas myostatin, a negative regulator of muscle growth and differentiation, was upregulated. The phenotypic deregulation of myogenic controllers in the presence of Ropivacaine was counteracted by AsA treatment. CONCLUSIONS: Our findings highlight the oxidative stress-mediated myotoxic effect of Ropivacaine on human skeletal muscle tissue cell cultures, and suggest treatment with AsA as valid strategy to mitigate its negative effects and allowing an ameliorated functional skeletal muscle recovery in patients undergoing hip replacement surgery for osteoporotic bone fracture.

Ultra-Low-Level Laser Therapy and Acupuncture Libralux: What Is so Special?

BACKGROUND: Contrary to the most credited theories on laser therapy that see power/energy as the major factors to its effectiveness, a technique using an extremely low power/energy laser stimulation to treat musculoskeletal pain and dysfunction is proposed. The stimulus consists of a 20 s train of modulated pulses with an average power below 0.02 mW and is applied on sequences of acupuncture points selected according to the impaired segment of the patient's body. Methods: Modifications on the extracellular soft tissue matrix and on the "fascia" were sonographically demonstrated. Laboratory and clinical tests confirmed the effectiveness. Results: Responses similar to those experienced in acupuncture were observed. The device-a CE Class IIa certified medical device named Libralux-affords a clinically proven effectiveness exceeding 80% in the treatment of musculoskeletal conditions and associated motor dysfunctions. An average of just three application sessions was generally sufficient to overcome the dysfunction. Conclusions: The development of the method is supported by over 20 years of R&D activities, with a range of experiments discussed in several papers published in indexed peer-reviewed journals. A few considerations regarding the possible physiological action mechanisms involved are proposed in this paper.