ISOLATION AND ANALYSIS OF EXTRACELLULAR MUSCLE FLUID FROM THE FROG

Abstract

Clear straw-colored fluid was collected from the extracellular spaces of frog muscle in calibrated capillary tubes by inserting the tubes length-wise into exposed leg muscles in situ. Histological examination showed that the muscle fibers had been neither torn nor penetrated but that the tubes were confined within the extracellular spaces. Cl analysis of this fluid (vol.= 1.0 cu.mm. on the avg.) was carried out by microelec-trometric titration. The ratio, serum chloride to fluid chloride, was 0.993 [plus or minus] 0.010. Erythrocyte counts averaged only 265 cells per cu.mm. of fluid indicating that it had not been collected from broken blood vessels. Chloride analysis of the muscles from which fluid samples had been drawn was also carried out, and, based on the ratio, muscle chloride to fluid chloride, showed that this fluid comprised 19.6% of the wt. of the muscle, assuming all chloride to be extracellular. The pH of the fluid, measured by capillary colorimetry, was the same as that of blood (7.2-7.4). The protein content of the fluid was compared gravimetrically with the serum protein from the same animal, showing an average of 1.53% as compared with serum protein of 4.23%. On the basis of the protein content the ratio, serum chloride to fluid chloride, was calculated on the assumption of a Donnan equilibrium, the value obtained being 0.975 as compared with the experimentally detd. value of 0.993.