1. INVESTIGATION INTO THE MECHANISM(S) OF NERVE COMPRESSION SYNDROMES AND OF OSTEOPATHIC MANIPULATIVE THERAPY
The unitary interaction of the systems of the body is a primary precept of osteopathy. In the case of the peripheral nervous system, while the gross morphological and some of the functional changes due to the severing and compression of peripheral motor nerves have been investigated and reported, the cellular effects of abnormal nerve signaling on the “end-organ” skeletal muscle cell have yet to be elucidated. And, while osteopathic manipulative therapy (OMT) can stimulate the body to maintain and repair itself (and to lessen problems due to afferent feedback to the central nervous system) and is used successfully in treatment of clinical nerve compressions including carpal tunnel, piriformis and thoracic outlet syndromes, there is no conclusive scientific evidence indicating the specific effects and mechanisms by which OMT alleviates these syndromes. Our laboratory continues to investigate the effects and mechanisms by which both denervation and compression of the rat sciatic nerve alters the function of muscle, assessing the effects of OMT in such syndromes. Initially we are qualifying and quantifying the effects of denervation and nerve compression on: 1) intact cell biochemistry; 2) the morphometry of single demembranated cells (fibers); and 3) the function of the contractile apparatus (i.e., the complex of actin, myosin and the regulatory proteins troponin and tropomyosin) of single demembranated fibers. Both fast- and slow-twitch fibers are being assessed. We are in the process of qualitatively and quantitatively defining the beneficial effects of OMT on: 1) amelioration of such effects; 2) in aiding recovery from nerve compression; and 3) comparing these benefits to those of an anti-oxidant therapy (AOT) and exercise training.
2. INVESTIGATION INTO MUSCLE FATIGUE MECHANISMS
This other major line of research is designed to understand the effect of the intracellular milieu on the contractile force and calcium-sensitivity and other functional and structural parameters of striated muscle. More specifically, to understand the mechanism(s) involved in the alteration of contractility by fatigue metabolites such as inorganic phosphate (Pi) and hydrogen ions (H+), both of which decrease force generation and calcium-sensitivity of striated muscle. The current working hypothesis of this laboratory is that Pi has at least some of its effect through binding to and destabilizing the contractile proteins. We are presently testing this hypothesis by using a group of methylamine compounds, which are known to stabilize proteins (these compounds have been previously been used in research involving the cryoprotection of proteins). Such chemicals include trimethylamine N-oxide (TMAO), betaine, and glycine. If the hypothesis is correct, these compounds should be able to reverse or ameliorate the effects of Pi and H+ by “protecting” muscle proteins from their binding to the myofilaments, thus returning force, calcium-sensitivity and other contractile parameters to control levels in a fatigued fiber. Previous experiments utilizing rabbit fast-twitch muscle have shown that TMAO increases maximal force production above control levels and ameliorates the force decrease seen in the presence of Pi, returning maximal force generating capacity back towards control values. Preliminary work is now underway to determine whether TMAO, betaine and/or glycine act similarly in cardiac muscle and whether these compounds can increase the calcium-sensitivity of the contractile proteins. Further experiments, utilizing gel electrophoresis, are being run to confirm the capacity of Pi to destabilize proteins and solubilized (“leach”) them into the bathing solution, similar experiments having shown this to be a possibility. Similar experiments will then be run in the presence of the methylamine compounds to determine whether these can protect the proteins from destabilization by Pi.