. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ION REGULATION IN EARTHWORMS 249 6. Trans epithelial electrical potentials The transepithelial electrical potential (TEP) generated by earthworms in vivo was measured as described by Dietz, Kirschner and Porter (1967). The basic bathing solution was 1 mM K2SO4 to obtain a conducting medium. Solutions were added to the bath to give the required ionic composition and concentration. 7. Statistical treatment All values for populations of animals are presented as the mean ± one standard error of the mean. Differences between mean
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ION REGULATION IN EARTHWORMS 249 6. Trans epithelial electrical potentials The transepithelial electrical potential (TEP) generated by earthworms in vivo was measured as described by Dietz, Kirschner and Porter (1967). The basic bathing solution was 1 mM K2SO4 to obtain a conducting medium. Solutions were added to the bath to give the required ionic composition and concentration. 7. Statistical treatment All values for populations of animals are presented as the mean ± one standard error of the mean. Differences between means were analyzed by the student "t" test and considered significant if P < RESULTS 1. Effect of ionic composition of the bath on CF composition Groups of six to eight worms were kept in baths of varying concentration of NaCl for 10 to 13 days whereupon the ionic composition of their CF was deter- mined. The results are shown in Figure 1. Earthworms hyper-regulate with respect to Na+ and total solute in solutions below 78 mM NaCl. Above this the CF remains slightly hyper-osmotic but the Na+ concentration is equal to the bath. Chloride is hyper-regulated in solutions below 40 mil/ NaCl but hypo- regulated above this. Over the entire range, Na+ and Cl~ account for most of the solute in CF. There is a slight increase in the total solute above that contributed by Na+ and Cl~ in the animals acclimated to 126 and 150 mM NaCl. The source is unknown. Potassium concentration is about 3 mM/1 and remained constant. z LLJ O u 250 200 150 100 50 LU O 288 Total Solute mOsM/l. 124 150 NaCl CONCENTRATION (mM/l) FIGURE 1. Coelomic fluid composition of Lumbricus terrestris acclimated 10 to 13 days in different NaCl solutions. Sodium is added to chloride in each column. The number adjacent to each bar is the mean concentration of the ion indicated (N = 8). Vertical lines indicate ± one The diagonal line represents Please note that these images are extracte
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
