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Unformatted text preview: o /[X] i ) E Na+ = 58 log (460/50) = 58 log 9.2 = 58 (0.964) = +55.9mV E Cl= 58 log (40/540) = 58 log (13.5) = 58 (1.13) = 65.6mV E K+ = 58 log (10/400) = 58 log (0.025) = 58 (1.60) = 92.9mV However, the membrane is permeable to more than one at a time. Using permeability to potassium as the reference, typical permeabilities of a membrane at rest are as follows: At rest: P K+ = 1.00 P Na+ = .03 P Cl= .10 The GoldmanKatz equation accounts for the contributions of all three ions: (P Na+ [Na + ] o + P K+ [K + ] o + P Cl[Cl] I ) E m = 58 log (P Na+ [Na + ] i + P K+ [K + ] i + P Cl[Cl] o ) (.03(460) + 1.0 (10) + .10 (40)) (13.8 + 10 + 4) 27.8 E rm = 58 log  = 58 log  = 58 log (.03 (50) + 1.0(400) + .10(540)) (1.5 + 400 + 54) 455.5 = 58 log (.061) = 58 (1.21) = 70.3mV...
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 Fall '08
 Stehouwer

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