Low frequency pulsed magnetic fields do not modify several aspects of ion transport in biological materials

The distributions and diffusivities of small ions in chondroitin sulphate, hyaluronate and some proteoglycan solutions

The distributions and diffusivities of Na+, Ca2+ and Cl- in chondroitin sulphate (CS), hyaluronate (HA) and proteoglycan solutions were measured using equilibrium dialysis and a capillary tube method. Measurements were made for a range of glycosaminoglycan (GAG) concentrations up to those normally found in dense connective tissue (10% CS, 2.5% HA), ionic strengths up to normal physiological concentrations (0.15 M) and for different combinations of monovalent and divalent cations. The partition coefficients, Ki, of the positive ions increased with increasing matrix concentration and with decreasing ionic strength but with one exception the selectivity coefficient KCaNa = square root of KCa/KNa was close to unity, indicating nearly ideal Donnan distributions. The ionic diffusivities decreased very much like those of small neutral solutes with increasing matrix concentration and with one exception were relatively independent of ionic strength, The exception in both cases was low matrix concentrations and low ionic strengths for which the diffusivity of Ca2+ was an order of magnitude lower and selectivity coefficients were approximately 2. We conclude that at physiological ionic strengths and GAG concentrations the distributions of small ions are determined by simple electrostatic interactions, without binding or condensation, and the diffusivities are not affected by the electrostatic field.

The action of pulsed magnetic fields on cyclic AMP levels in cultured fibroblasts

Pulsed magnetic fields, similar to those used clinically to promote bone repair, have been applied to cultured fibroblasts obtained from chick embryo tendons and rabbit bone marrow. Cyclic adenosine monophosphate (cAMP) levels were found to be lower in field-treated cultures in response to hormones such as prostaglandin E2 and isoproterenol, and the fibroblasts appear less sensitive to environmental perturbation prior to hormone incubation. We propose that the adenylate cyclase complex is temporarily inactivated by prolonged exposure to pulsed magnetic fields, and that this effect might be analogous to desensitisation phenomena.