1. The current-voltage relation of the smooth muscle cell membrane of rabbit aorta was determined by the partition method. 2. No anomalous rectification was observed in any of the following solutions: normal Krebs, Na free choline, Na sulphate, and high K-Na free sulphate. 3. Delayed rectification was seen on application of depolarizing current in both normal Krebs solution and Na free choline solution. 4. High concentration of K made the steady-state current-voltage relation almost linear in a voltage range of about 0 to -20mV. This effect, and steady-state cathodal rectification which was seen in physiological solution, could be explained qualitatively by constant field theory without involving channels capable of anomalous rectification. 5. A slow decrease in K conductance, during application of large and long-lasting hyperpolarizing currents, which occurs in skeletal muscle and is attributed to the tubule system, was never observed in the arteries either in Krebs, Na-free choline, or Na sulphate solution.
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