Bioelectric response of human nasal epithelial cells to
polycationic protein.
Scott, M. R. Van, M. D. Smith, C. A. Welch, C. Bentzel, and W. J.
Metzger.
Departments of Physiology and *Medicine, East Carolina University
School of Medicine, Greenville, NC 27858
APStracts 3:0049L, 1996.
Polycationic proteins alter electrolyte transport by epithelia and
endothelium, and in asthma are thought to disrupt the airway
epithelium and contribute to hyperresponsiveness and airway plugging.
In the present study, we used primary cultures of human nasal
epithelial cells to investigate the response of respiratory tract
epithelium to lumenal presentation of a polycationic protein,
protamine. Protamine (100 [mu]g/ml) in the apical bathing solution
had no significant effect on basal transepithelial resistance (Rt),
but decreased short circuit current (Isc) and hyperpolarized the
apical membrane indicating that Na+ absorpition had been inhibited.
Pretreating with amiloride inverted the response to protamine
resulting in an increase in Isc, depolarization of the apical
membrane and decrease in the fractional resistance of the apical
membrane (fRa). The increase in Isc was inhibited by pretreatment
with bumetanide. These results indicated that protamine augmented
amiloride-induced Cl- secretion. Induction of Cl- secretion by
bathing the apical surface in 3 mM Cl-- Ringers solution likewise
resulted in protamine-induced depolarization of the apical membrane.
Heparin precipitated protamine from solution and reversed the Isc
responses. In summary, low concentrations of polycationic protein can
alter electrolyte transport by human airway epithelium without
desquamation, and the response is dependent on the secretory state of
the tissue.
Received 19 July 1995; accepted in final form 18 March 1996.
APS Manuscript Number L227-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 April 96