Remote Dose-Dependent Effects of Dry Needling at Distant Myofascial Trigger Spots of Rabbit Skeletal Muscles on Reduction of Substance P Levels of Proximal Muscle and Spinal Cords

Background. Dry needling at distant myofascial trigger points is an effective pain management in patients with myofascial pain. However, the biochemical effects of remote dry needling are not well understood. This study evaluates the remote effects of dry needling with different dosages on the expressions of substance P (SP) in the proximal muscle, spinal dorsal horns of rabbits.Methods. Male New Zealand rabbits (2.5–3.0 kg) received dry needling at myofascial trigger spots of a gastrocnemius (distant muscle) in one (1D) or five sessions (5D). Bilateral biceps femoris (proximal muscles) and superficial laminaes of L5-S2, T2-T5, and C2-C5 were sampled immediately and 5 days after dry needling to determine the levels of SP using immunohistochemistry and western blot.Results. Immediately after dry needling for 1D and 5D, the expressions of SP were significantly decreased in ipsilateral biceps femoris and bilateral spinal superficial laminaes (P<.05). Five days after dry needling, these reduced immunoactivities of SP were found only in animals receiving 5D dry needling (P<.05).Conclusions. This remote effect of dry needling involves the reduction of SP levels in proximal muscle and spinal superficial laminaes, which may be closely associated with the control of myofascial pain.

Dry Needling at Myofascial Trigger Spots of Rabbit Skeletal Muscles Modulates the Biochemicals Associated with Pain, Inflammation, and Hypoxia

Background and Purpose. Dry needling is an effective therapy for the treatment of pain associated with myofascial trigger point (MTrP). However, the biochemical effects of dry needling that are associated with pain, inflammation, and hypoxia are unclear. This study investigated the activities ofβ-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF after different dosages of dry needling at the myofascial trigger spots (MTrSs) of a skeletal muscle in rabbit. Materials and Methods. Dry needling was performed either with one dosage (1D) or five dosages (5D) into the biceps femoris with MTrSs in New Zealand rabbits. Biceps femoris, serum, and dorsal root ganglion (DRG) were sampled immediately and 5 d after dry needling forβ-endorphin, substance P, TNF-α, COX-2, HIF-1α, iNOS, and VEGF immunoassays.Results. The 1D treatment enhanced theβ-endorphin levels in the biceps femoris and serum and reduced substance P in the biceps femoris and DRG. The 5D treatment reversed these effects and was accompanied by increase of TNF-α, COX-2, HIF-1α, iNOS, and VEGF production in the biceps femoris. Moreover, the higher levels of these biochemicals were still maintained 5 d after treatment.Conclusion. Dry needling at the MTrSs modulates various biochemicals associated with pain, inflammation, and hypoxia in a dose-dependent manner.

Halothane and Isoflurane Do Not Directly Interact with Cardiac Cross-bridge Function

Background Halogenated anesthetics depress myocardial contractility by altering a number of specific mechanisms. These alterations include decreases in inward calcium current and sarcoplasmic reticulum function and reduced calcium myofilament sensitivity. However, the direct effects of volatile anesthetics on cross-bridge function have yet to be precisely determined. Methods Myosin monomers and actin filaments were isolated from fresh rat left ventricles and rabbit skeletal muscles, respectively. Halothane or isoflurane was added at concentrations equivalent to 1 and 2 minimum alveolar concentration (MAC). Motility of actin filaments over myosin was initiated by adding 2 mm adenosine triphosphate and was analyzed at 30 degrees C. Maximum actomyosin adenosine triphosphatase activity and the association constant of myosin for actin were determined from a double-reciprocal Lineweaver-Burk plot of the adenosine triphosphatase rate versus actin concentration. A known inhibitor of actomyosin function, 2,3-butanedione 2-monoxime (2 mm), was used in positive control experiments. Data are presented as mean +/- SD. Results Motility velocities driven by myosin were not significantly different between baseline and 1 and 2 MAC halothane (2.70 +/- 0.33, 2.72 +/- 0.36, and 2.70 +/- 0.40 microm/s, respectively). Similarly, motility velocities driven by myosin were not significantly different between baseline and 1 and 2 MAC isoflurane (2.73 +/- 0.33, 2.72 +/- 0.37, and 2.72 +/- 0.40 microm/s, respectively). Neither of the two halogenated anesthetics, at any concentration tested, significantly modified the maximum actomyosin adenosine triphosphatase activity or the association constant of myosin for actin as compared with baseline. 2,3-Butanedione 2-monoxime induced a drastic reduction in both motility velocity and maximum actomyosin adenosine triphosphatase activity. Conclusion These results indicate that isoflurane and halothane do not directly depress the mechanical or enzymatic properties of cross-bridges in the heart.