title: INFLUENCE OF SOME IONS ON THE MEMBRANE POTENTIAL OF ASCARIS MUSCLE.
abstract: The influence of several ions on the membrane potential of the somatic muscle of Ascaris has been investigated by changing their concentration in the surrounding solution. When [K](o) is increased at the expense of [Na](o) leaving [Cl](o) constant, the membrane potential is first seen to increase. [K](o) higher than 45 mM reduces the membrane potential with a slope of 23 mv for a tenfold change in [K](o). However, when [K](o) is increased keeping [Na](o) and [Cl](o) low and constant, the line relating the membrane potential with log [K](o) has a slope of almost 50 mv. If [Cl](o) is reduced in the absence of external Na, after the [K](o) is increased to 45 mM, the membrane potential decreases with a slope of 59 mv per tenfold change in [Cl](o) in close agreement with the Nernst equation. If Cl(-) is replaced by SO(4) (2-), a depolarization is produced, while chloride replacement by NO(3) (-), Br(-), and I(-) results in a hyperpolarization of the membrane. Removal of the external Na(+) ions increases the average membrane potential by 17 mv.
mesh_terms: D000818:Animals; D001200:Ascaris; D001639:Bicarbonates; D001965:Bromides; D002118:Calcium; D002712:Chlorides; D004594:Electrophysiology; D007454:Iodides; D007477:Ions; D008274:Magnesium; D008564:Membrane Potentials; D009132:Muscles; D009566:Nitrates; D011188:Potassium; D012106:Research; D012964:Sodium
chemical_list: D001639:Bicarbonates; D001965:Bromides; D002712:Chlorides; D007454:Iodides; D007477:Ions; D009566:Nitrates; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium
keywords: ASCARIS; BICARBONATES; BROMIDES; CALCIUM; CHLORIDES; ELECTROPHYSIOLOGY; EXPERIMENTAL LAB STUDY; IODIDES; MAGNESIUM; MUSCLES; NITRATES; POTASSIUM; SODIUM