The Journal of Membrane Biology

, Volume 87, Issue 2, pp 141–150

Protamine reversibly decreases paracellular cation permeability inNecturus gallbladder

  • Michael Fromm
  • Carlos E. Palant
  • Carl J. Bentzel
  • Ulrich Hegel
Articles

DOI: 10.1007/BF01870660

Cite this article as:
Fromm, M., Palant, C.E., Bentzel, C.J. et al. J. Membrain Biol. (1985) 87: 141. doi:10.1007/BF01870660

Summary

Protamine, a naturally occurring arginine-rich polycationic protein (pI 9.7 to 12), was tested inNecturus gallbladder using a transepithelial AC-impedance technique. Protamine sulfate or hydrochloride (100 μg/ml=20 μm), dissolved in the mucosal bath, increased transepithelial resistance by 89% without affecting the resistance of subepithelial layers. At the same time, transepithelial voltage (ψms) turned from slightly mucosapositive values to mucosa-negative values of approximately +1 to −5 mV. The effect of protamine on transepithelial resistance was minimal at concentrations below 5 μg/ml but a maximum response was achieved between 10 and 20 μg/ml. Resistance started to increase within 1 min and was maximal after 10 min. These effects were not inhibited by serosal ouabain (5×10−4m) but could be readily reversed by mucosal heparin. The sequence of protamine effect and heparin reversal could be repeated several times in the same gallbladder. Mucosal heparin, a strong negatively charged mucopolysaccharide, or serosal protamine were without effect. Mucosal protamine reversibly decreased the partial ionic conductance of K and Na by a factor of 3, but did not affect Cl conductance. Net water transport from mucosa to serosa was reversibly increased by 60% by protamine. We conclude that protamine reversibly decreases the conductance of the cation-selective pathway through the tight junction. Although this effect is similar to that reported for 2,4,6-triamino-pyrimidinium (TAP), the mechanism of action may differ. We propose that protamine binds to the apical cell membrane and induces a series of intracellular events which leads to a conformational alteration of the tight junction structure resulting in decreased cationic permeability.

Key Words

protamineNecturus gallbladdertight junctionimpedance analysistransepithelial resistance

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Michael Fromm
    • 1
  • Carlos E. Palant
    • 2
  • Carl J. Bentzel
    • 2
  • Ulrich Hegel
    • 1
  1. 1.Institut für Klinische PhysiologieFreie Universität BerlinBerlin 45Federal Republic of Germany
  2. 2.State University of New York at Buffalo and VA Medical CenterBuffalo
  3. 3.Nephrology DivisionSepulveda VA Medical CenterSepulveda
  4. 4.Division of Renal MedicineEast Carolina University School of MedicineGreenville