Journal of Applied Physiology, Vol 76, Issue 4 1489-1493, Copyright © 1994 by American Physiological Society
Decreased ion transport by tracheal epithelium of the basenji-greyhound dog
T. L. Croxton, M. Takahashi and C. A. Hirshman
Department of Environmental Health Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
The Basenji-Greyhound (BG) dog model shows altered beta-adrenergic function
in both airway smooth muscle and leukocytes. To investigate a possible
beta-adrenergic pathway defect in airway epithelial cells of BG dogs, we
studied the electrophysiological behavior of tracheal epithelia in vitro
and measured tracheal electrical potentials in vivo. Baseline short-circuit
currents of isolated tracheal epithelia from BG (n = 6) and mongrel control
dogs (n = 7) were 18.7 +/- 3.4 and 43.7 +/- 4.2 microA/cm2, respectively (P
= 0.001). Significant differences between short-circuit currents of BG and
control epithelia persisted after inhibition of Cl- secretion by
indomethacin or stimulation by isoproterenol or dibutyryl adenosine
3',5'-cyclic monophosphate. In vivo tracheal potentials were also
significantly less (P = 0.01) in BG dogs (-22.3 +/- 2.5 mV; n = 12) than in
control dogs (-32.5 +/- 2.6 mV; n = 10), and intravenous indomethacin
reduced the tracheal potential of BG dogs but had no effect in control
animals. There was no correlation in BG dogs between tracheal potential and
the dose of methacholine required to double total lung resistance. These
data suggest that ion transport by tracheal epithelium is decreased in BG
dogs, that this difference is not due to diminished beta-adrenergic
activity, and that cyclooxygenase products are important in maintaining
tracheal potential in vivo in this model.
