Decreased ion transport by tracheal epithelium of the basenji-greyhound dog.
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.
Croxton
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TL
Department of Environmental Health Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Takahashi
M
M
Hirshman
C A
CA
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004285:Dogs; D004594:Electrophysiology; D004848:Epithelium / Q000378:metabolism; D005260:Female; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008688:Methacholine Compounds / Q000494:pharmacology; D014132:Trachea / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D008688:Methacholine Compounds; D003994:Bucladesine; D000242:Cyclic AMP; D007213:Indomethacin