ISSN:
1432-1424
Keywords:
nystatin
;
amiloride
;
basolateral membrane
;
toad urinary bladder
;
Na+ transport
;
epithelial impedance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Exposing the apical membrane of toad urinary bladder to the ionophore nystatin lowers its resistance to less than 100 Ω cm2. The basolateral membrane can then be studied by means of transepithelial measurements. If the mucosal solution contains more than 5mm Na+, and serosal Na+ is substituted by K+, Cs+, or N-methyl-d-glucamine, the basolateral membrane expresses what appears to be a large Na+ conductance, passing strong currents out of the cell. This pathway is insensitive to ouabain or vanadate and does not require serosal or mucosal Ca2+. In Cl-free SO 4 2− Ringer's solution it is the major conductive pathway in the basolateral membrane even though the serosal side has 60mm K+. This pathway can be blocked by serosal amiloride (K i=13.1 μm) or serosal Na+ ions (K i∼ 10 to 20mm). It also conducts Li+ and shows a voltage-dependent relaxation with characteristic rates of 10 to 20 rad sec−1 at 0 mV.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01869154
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