E NEW YORK s raIn 10己 Difference between Ek and directly measured resting potential Ek Observed RP Mammalian skeletal muscle cell 95 mV 90 mV Frog skeletal muscle cell -105mV-90mV Squid giant axon 96 mV 70 mV
Mammalian skeletal muscle cell -95 mV -90 mV Frog skeletal muscle cell -105 mV-90 mV Squid giant axon -96 mV -70 mV Ek Observed RP Difference between EK and directly measured resting potential
E NEW YORK s raIn 10己 A K K Cl Na Na Inside Outside cell ce Goldman-Hodgkin-Katz equation RT/[K'Jo+PNa[Na]+Pa[CIl F(PKIK]+ PNa[Na*]+pa[CI lo
Goldman-Hodgkin-Katz equation
Intracellular tulo Extracellular nuid raIn 10己 Na+ 3 Na' K.ATPa Role of Nat-K+ pump K Electrogenic Hyperpolarizing Intracellular fluld tracellular n Na+ Establishment of resting K+ membrane potential Na+/K+ pump establishes concentration gradient Intracellular fluid Extracellular nuid generating a small + negative potential; pump 3Na° uses up to 40% of the ATP produced by that K+ cell!
•Electrogenic •Hyperpolarizing Role of Na+-K + pump: Establishment of resting membrane potential: Na+/K+ pump establishes concentration gradient generating a small negative potential; pump uses up to 40% of the ATP produced by that cell!
E NEW YORK s raIn 10己 Origin of the normal resting membrane potential Kt diffusion potential Nat diffusion Nat-K pump
Origin of the normal resting membrane potential K+ diffusion potential Na+ diffusion Na+-K+ pump
20 c-40 Experimenta observations 60 80 Nernst equation 100 E=-61I0o C/ 120 00.20.51.02.55102050100 B Potassium concentration (mM)