Sudden potential drop in bullfrog gastric mucosa.
The previously reported sudden potential drop (SPD), which occurs under anoxia in 10% CO2, has been further explored. We find several conditions necessary for this effect: 1) anoxia; 2) serosal pH less than 7.1;3) presence of chloride; and 4) a PD, either spontaneous or voltage clamped, which changes across the region of 10 mV, serosal positive. With the first three conditions satisfied, a reversible decrease in measured resistance can be produced at will by changing the clamp voltage. In the anoxic, low-resistance state, changes in K+ or C1- concentration give little change in voltage, showing that the increased conductivity is not selective for either ion. A model is proposed containing a shunt-resistance element whose resistance is a step function of PD. This model can mimic the responses of the tissue and provides a working model for the SPD.
D000818:Animals; D001001:Anura; D002245:Carbon Dioxide / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology; D004594:Electrophysiology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000503:physiopathology; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000503:physiopathology; D008954:Models, Biological; D010100:Oxygen; D010539:Permeability; D011188:Potassium / Q000378:metabolism; D011892:Rana catesbeiana
D002712:Chlorides; D002245:Carbon Dioxide; D011188:Potassium; D010100:Oxygen