Inward rectification in submucosal arterioles of guinea-pig ileum.

1. The current-voltage relationships of short segments of submucosal arteriole of guinea-pig have been determined using constant current and voltage clamp techniques. 2. The current-voltage relationships were non-linear over the membrane potential range -60 to -90 mV, the conductance increasing with hyperpolarization. 3. The membrane potential ranges over which the membrane conductance increased were changed by changing the external concentration of potassium ions. 4. Changing the external concentrations of sodium and chloride ions had no effect on the arteriolar current-voltage relationships. 5. The hyperpolarization-activated conductance increase was prevented by low concentrations of barium ions. 6. It is suggested that these arterioles display potassium-selective inward rectification and that the rectifier supplies the dominant resting potassium conductance. The properties of this rectifier are compared with those of other tissues.