The Effect of BaCl2 on the Resting Membrane Potential of the Superior Flexor Muscle of Crayfish, Procambarus clarkii.

Barium ions block potassium leak channels that contribute to the resting membrane potential in most animal cells (Armstrong and Taylor, 1980). Here we examine the impact of barium on the resting membrane potential of crayfish superficial flexor muscles by replacing the calcium chloride in normal crayfish Ringer's solution with barium chloride. Replacement of calcium chloride with barium chloride resulted in an increase in the resting membrane potential of the tail muscles. Increasing the concentration of barium chloride resulted in an increasingly more positive resting membrane potential. To determine that this effect was not caused by the absence of calcium, barium chloride and calcium chloride were replaced with magnesium chloride in the Ringer's solution. There was no significant difference in the resting membrane potential between the control and magnesium solutions. Barium has been linked with toxicity effects in humans leading to hypokalemia, which is a condition of having low potassium levels within the bloodstream. This may lead to cardiac arrhythmias and muscle weakness. This can be explained, in part, by the direct effect of barium on potassium channels. [ABSTRACT FROM AUTHOR]