Journal of Applied Physiology, Vol 62, Issue 3 972-977, Copyright © 1987 by American Physiological Society
Homeostatic regulation of airway smooth muscle tone by catecholamine secretion in swine
S. R. White, M. F. Sands, K. J. Popovich, T. M. Murphy, N. M. Munoz, J. Blake, M. Mack, T. Shioya and A. R. Leff
We studied the homeostatic secretory response of catecholamine secretion
elicited by progressive bronchoconstriction in 18 swine in vivo. The
potential reserve of the sympathetic nervous system (SNS) was first
assessed by exogenous nicotinic stimulation with
1,1-dimethyl-4-phenylpiperazinium iodide (DMPP). A dose of 250
micrograms/kg iv DMPP caused an increase in plasma norepinephrine (NE)
concentration from 207 +/- 86 (basal) to 2,625 +/- 448 pg/ml (P less than
0.02) and in plasma epinephrine (EPI) from 10 +/- 5.0 to 1,410 +/- 432
pg/ml (P less than 0.05) in four swine. In four other swine,
bronchoconstriction induced by aerosolized prostaglandin F2 alpha caused
approximately a fivefold increase in airway resistance without hemodynamic
changes. No increase in plasma EPI was observed. However, plasma NE
increased from 330 +/- 131 to 1,540 +/- 182 pg/ml (P less than 0.02). In
five swine receiving aerosolized acetylcholine (ACh), similar changes in
airways resistance were not associated with significant changes in
catecholamine concentration when mean arterial blood pressure (MAP) was
unchanged. However, inhalation of sufficient ACh to cause a greater than
10% decrease in MAP caused progressive increase in catecholamine secretion.
Plasma EPI increased from 32 +/- 16 (MAP = 124 +/- 7 Torr) to 1,165 +/- 522
pg/ml (MAP = 94 +/- Torr). Hypoxemia that occurred with bronchoconstriction
(greater than or equal to 50 Torr) did not cause catecholamine secretion.
However, severe hypoxemia (PO2 less than 30 Torr) caused large increases in
plasma EPI concentrations from 84 +/- 27 to 1,463 +/- 945 pg/ml (P less
than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
