AJP - Lung Cellular and Molecular Physiology, Vol 268, Issue 3 519-L525, Copyright © 1995 by American Physiological Society
Assessment of agonist- and cell-mediated responses in airway microsections by computerized videomicrometry
S. Galens, N. M. Munoz, K. F. Rabe, A. Herrnreiter, D. Mayer, B. Morton, K. McAllister and A. R. Leff
Department of Medicine, University of Chicago, Illinois 60637.
The objective of this investigation was to develop a method for real-time
measurement of changes in luminal area in microexplants of airways during
pharmacological and physiological interventions. After guinea pigs were
killed, tracheal rings (1- to 2-mm thick) were excised and placed in
300-microliters chambers. The area of the airway lumen was calculated as
pixel number with the use of computerized videomicrometry. In 29
epithelium-intact airways, 10(-3) M acetylcholine (ACh) caused decrease in
luminal area of 38.1 +/- 2.80% (P < 0.001 vs. 10(-9) M). Spontaneous
tone also was demonstrated in 34 preparations from 4 guinea pigs; decrease
in area of 17.0 +/- 1.45% after 60-min incubation in buffer alone was
blocked completely by 10(-5) M indomethacin (P = 0.01). Luminal narrowing
caused by < or = 10(-6) M ACh was reversed completely by 10(-6) M
albuterol (P = 0.002). Addition of 100,000 activated human eosinophils
caused 24.7 +/- 4.41% decrease in luminal area vs. 7.24 +/- 5.51% for
nonactivated cells (P = 0.048). We demonstrate a real-time method for the
assessment of auxotonic changes in airway caliber that utilizes
microsections of explanted airways and permits the use of extremely small
numbers of isolated cells to achieve physiological activation.
Concentration-response characteristics and spontaneous tone are similar to
those of large chamber preparations, and narrowing is reversed by beta
2-adrenoceptor activation.
