Glass micropipette electrodes have been employed to study the transsurface potential difference of @entity1980 . For mature hyphae grown in agar cultures, the internal potential is large and negative, often exceeding -200 mv. The potential is sensitive to the concentrations of extracellular @entity972 , @entity1372 , @entity3884 , and @entity460 ions, but does not vary in a manner which is readily explained by ionic diffusion potentials. With extracellular solutions containing only @entity4337 (or @entity597 ) and @entity969 , the internal potential shifts toward zero (becomes less negative) at 45 mv per tenfold increase of @entity972 , over the range 0.1 to 10 mM. A similar result has been found with @entity1372 , though the slope is only 33 mv/log unit. @entity460 (1 mM) diminishes the influence of @entity972 and @entity1372 by 60 to 70 per cent. As @entity972 or @entity1372 is raised above 20 mM, the slope of the internal potential increases sharply to 85 to 90 mv/log unit, both in the presence and absence of @entity460 . With increasing @entity3884 ion concentration, too, the internal potential shifts toward zero; in this case the slope is about 12 mv/pH unit at pH 9 and rises smoothly to 33 mv/pH unit at pH 3. All these phenomena are probably properties of the plasma membrane. The polysaccharide cell wall contains few fixed negative charges, has a low transverse resistance, and supports very little potential difference when separated from the plasma membrane.

Electrical properties of XXXX . Effects of external cations on the intracellular potential.

@entity3884 :: ('MESH:D006859', 'Chemical') :: ['hydrogen'] @entity1372 :: ('MESH:D012964', 'Chemical') :: ['sodium'] @entity1980 :: ('5141', 'Species') :: ['Neurospora crassa'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium', 'Calcium'] @entity972 :: ('MESH:D011188', 'Chemical') :: ['potassium'] @entity4337 :: ('MESH:D011189', 'Chemical') :: ['potassium chloride'] @entity597 :: ('CHEBI:16189', 'Chemical') :: ['sulfate']
@entity1980 :: (5141,Species) :: ['Neurospora crassa']
