The Journal of Membrane Biology

, Volume 79, Issue 3, pp 257–269

Electrophysiology ofNecturus urinary bladder: II. Time-dependent current-voltage relations of the basolateral membranes

  • Stanley G. Schultz
  • Stephen M. Thompson
  • Randall Hudson
  • S. Randall Thomas
  • Yuichi Suzuki
Articles

DOI: 10.1007/BF01871064

Cite this article as:
Schultz, S.G., Thompson, S.M., Hudson, R. et al. J. Membrain Biol. (1984) 79: 257. doi:10.1007/BF01871064

Summary

As reported previously (S.R. Thomas et al.,J. Membrane Biol.73:157–175, 1983) the current-voltage (I–V) relations of the Na-entry step across the apical membrane of short-circuitedNecturus urinary bladder in the presence of varying mucosal Na concentrations are (i) time-independent between 20–90 msec and (ii) conform to the Goldman-Hodgkin-Katz constant field flux equation for a single cation over a wide range of voltages.

In contrast, theI–V relations of the basolateral membrane under these conditions are (i) essentially linear between the steady-state, short-circuited condition and the reversal potential (Es); and (ii) are decidedly time-dependent withEs increasing and the slope conductance,Es, decreasing between 20 and 90 msec after displacing the transepithelial electrical potential difference. Evidence is presented that this time-dependence cannot be attributed entirely to the electrical capacitance of the tissue.

The values ofgs determined at 20 msec are linear functions of the short-circuit current,Isc, confirming the relations reported previously, which were obtained using a more indirect approach.

The values ofEs determined at 20 msec are significantly lower than any reasonable estimate of the electromotive force for K across the basolateral membrane, indicating that this barrier possesses a significant conductance to other ions which may exceed that to K. In addition, these values increase linearly with decreasingIsc and approach the value of the electrical potential difference across the basolateral membrane observed when Na entry across the apical membrane is blocked with amiloride or when Na is removed from the mucosal solution.

A possible explanation for the time-dependence ofEs andgs is offered and the implications of these findings regarding the interpretation of previous microelectrophysiologic studies of epithelia are discussed.

Key Words

current-voltage relations basolateral membranes Necturus urinary bladder membrane capacitance time-dependentI–V relations 

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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Stanley G. Schultz
    • 1
  • Stephen M. Thompson
    • 1
  • Randall Hudson
    • 1
  • S. Randall Thomas
    • 1
  • Yuichi Suzuki
    • 1
  1. 1.Department of Physiology and Cell BiologyUniversity of Texas School of MedicineHouston
  2. 2.Laboratoire de Physiologie RenaleHospital des Enfants Malades, I.N.S.E.R.M., U. 192ParisFrance
  3. 3.Department of PhysiologyYamagata University School of MedicineYamagataJapan

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