AJP - Cell Physiology, Vol 259, Issue 3 C450-C454, Copyright © 1990 by American Physiological Society
Duramycin enhances chloride secretion in airway epithelium
M. M. Cloutier, L. Guernsey, P. Mattes and B. Koeppen
Department of Pediatrics, University of Connecticut Health Center, Farmington 06032.
The effect of duramycin, a polypeptide antibiotic, on Cl- transport in
canine tracheal epithelium mounted in Ussing chambers was studied. Over a
narrow concentration range, duramycin increased short-circuit current (Isc)
and net Cl- secretion and had no effect on mannitol flux when added to the
mucosal bathing solution. The maximum increase in Isc was observed at a
duramycin concentration of 2 X 10(-6) M and was associated with an increase
in both unidirectional Cl- fluxes. Higher duramycin concentrations produced
a decrease in Isc. Submucosal addition of duramycin had no effect on Isc
except at high concentrations. Pretreatment of tissues with mucosal
amiloride (10(-4) M) to reduce basal Na+ transport had no effect on the
subsequent response to duamycin. In other tissues pretreated with 10(-3) M
dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP), duramycin produced a
further increase in Isc and net Cl- secretion similar to its effect in
nonpretreated tissues. In all instances the increase in Isc was entirely
accounted for by an increase in net Cl- secretion. We conclude that
duramycin increases Isc and Cl- secretion in airway epithelium. Although
the mechanism of activation is not known, these data demonstrate that
duramycin increases Cl- secretion by a pathway other than cAMP. An
understanding of the mechanism of action of duramycin may further our
understanding of Cl- secretion regulation in airway epithelium.
