The effect of mechanical deformation on the distribution of ions in fibroblasts

The extracellular and intracellular sodium, potassium and chloride concentrations were determined in fibroblast cells located in the rat calvarium. The ionic values were determined by fluorescence microscopy after incubation with the fluorescent probes, sodium-binding benzofuran isophthalate (SBFI), potassium-binding benzofuran isophthalate (PBFI) and 6-methoxy-N-(3-sulfopropyl) quinolinium (SPQ) (Dyes were supplied by CALBIOCHEM, Nottingham, England). After determination of the resting membrane potential, the calvaria were placed under tension by retraction of a micromanipulator. The fluorescence was measured again. A statistically significant difference was found in the calculated potassium ion concentration (Mann-Whitney; p < 0.05). This affected the resting cell membrane potential by an average of 5.2 mV. This effect was blocked by the addition of a Potassium Channel blocker, tetraethylammonium (TEA).