ABSTRACT
The mean resting potential in the heart ventricle muscle cells of the freshwater snail Lymnaea stagnalis was found to be – 61·2±3·5(..)mV (ranging from –56mV to –68mV). The average intracellular potassium concentration was estimated to be 51·5 ± 14·6 (..) m (ranging from 27·8 m to 77·3 m). The membrane of the heart ventricle muscle cells appears to be permeable to both potassium and chloride, as changes in the extracellular concentration of either of these ions resulted in a change in the membrane potential. A ten-fold change in the extracellular potassium concentration was associated with a 50·4 ± 3·8 (..) mV slope when the potassium concentration was above about 6 m. Deviations from the straight-line relation predicted for a potassium electrode could be accounted for by introducing a term for sodium permeability. The ionic basis of the membrane potential in these cells can be described by a modified form of the Goldman-Hodgkin-Katz equation.
