Regulation of ion transport across porcine distal bronchi.
Inglis, Sarah K., Michel R. Corboz, Aubrey E. Taylor, and Stephen T.
Ballard.
Department of Physiology, College of Medicine, University of South
Alabama, Mobile, AL 36688
APStracts 2:0175L, 1995.
Distal airways comprise the vast majority of total human airway
surface area, yet little is known about transepithelial ion transport
in these tissues. Pathways that regulate ion transport in porcine
small bronchi (3.62 +/- 0.04mm outer diameter) were studied by
measuring the effects of secretogogues that stimulate Cl- secretion
in proximal airways. Resting PD, short-circuit current (ISC) and
resistance (Rt) across the distal bronchi were 3.4 +/- 0.1mV (lumen
negative), 40.8 +/- 1.7_A x cm-2 and 92.1 +/- 5.0[omega] x cm2,
respectively. Isoproterenol (10_M), acetylcholine ACh (10_M) or ATP
(100_M) induced immediate significant (p<0.05) increases in PD
and ISC. The Ca2+ ionophore A23187 (1_M) induced a slow increase in
PD that was accompanied by a significant 2.4 fold increase in Rt and
no change in ISC. The responses to isoproterenol, ACh and ATP were
maintained in the presence of 10_M amiloride. Pretreatment with 10_M
bumetanide to block Cl- secretion inhibited responses to
isoproterenol and ATP but not to ACh. The ACh effect was inhibited
only after both Cl- and HCO3- secretion were blocked. These data
suggest that isoproterenol, ACh and ATP stimulate anion secretion.
Isoproterenol and ATP specifically stimulate Cl- secretion whereas
ACh can stimulate both Cl- and HCO3- secretion. A23187 has no effect
on active transepithelial ion transport but increases barrier
resistance in intact distal bronchial epithelium.
Received 31 March 1995; accepted in final form 18 September 1995.
APS Manuscript Number L99-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95