The effects of the replacement of K+ by Tl+, Rb+, and NH+4 on the muscle membrane potential.
The resting membrane potential (RMP) of mouse diaphragm muscle was measured in solutions containing several concentrations of K+ (0.4 to 5 mmol/l) or one of the following cations: Tl+ (0.4, 1 or 2 mmol/l), Rb+ (1, 2 or 5 mmol/l), or NH+4 (4, 8 or 16 mmol/l). In terms of controlling the RMP, the ratios of the efficacies were Tl+:K+:Rb+:NH+4 = 2.5:1.0:1.0:0.12. These ratios are similar to those of the selectivities of the voltage dependent K+ channel (delayed rectifier) in frog nerve and muscle, and this similarity suggests that the resting membrane potential may be controlled by this channel.
D000641:Ammonia / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000502:physiology; D005260:Female; D007473:Ion Channels / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D012413:Rubidium / Q000494:pharmacology*; D013691:Tellurium / Q000494:pharmacology*
D007473:Ion Channels; D000641:Ammonia; D012413:Rubidium; D013691:Tellurium; D011188:Potassium