Exercises 43-4? picture a voltage clamp that shifts from H" at -6I'J m'v' to V... = 15 m'v. At rst the clamp is performed with the normal composition of [Na].- = 15 mivl and [N a]... = 13!} mM. 43. The early current is carried by which ion. and crossing in which direction? 44. The srendpsrnrs cunent is carried by which ion. and crossing in which direction? 45. If the voltage clamp is repeated such that the sodium current is abolished. what extracellular medium changes are necessary? {Be specic and quantitative.) 45. If the voltage clamp at bi... = 15 ni'la" is conducted with 10% sodium seawater {[Na].. = 13.0 mMJ. how does the sodium current magnitude and time course compare with that under normal conditions? [Be specic and quantitative.) 4?. How does the potassium ion flow compare during the voltage clamp under normal. zero sodium ux. 10% sodium seawater conditions