Dose-response relationship between plasma epinephrine concentration and alveolar liquid clearance in dogs

Previously, alveolar liquid clearance (ALC) was observed to increase in a canine model of neurogenic pulmonary edema (NPE) by adrenal epinephrine (S. M. Lane, K. C. Maender, N. E. Awender, and M. B. Maron. Am. J. Respir. Crit. Care Med. 158: 760-768, 1998). In this study the dose-response relationship between plasma epinephrine concentration and ALC was determined in anesthetized dogs by infusing epinephrine to produce plasma concentrations of 256 +/- 37, 1,387 +/- 51, 15,737 +/- 2,161, and 363,997 +/- 66,984 (SE) pg/ml (n = 6 for each concentration) for 4 h and measuring the resultant ALC. The latter was determined by mass balance after instillation of autologous plasma into a lower lung lobe. These plasma concentrations produced ALCs of 14.3 +/- 1.2, 20.5 +/- 1.9, 30.1 +/- 1.5, and 37.9 +/- 2.7% of the instilled volume, respectively. ALC after the lowest infusion rate was not different from that previously observed under baseline conditions (14.1 +/- 2.1%), whereas in a previous study of NPE, plasma epinephrine concentration increased to 7,683 +/- 687 pg/ml and ALC was 30.4 +/- 1.6%. These data indicate that, during recovery from canine NPE, ALC is not maximally stimulated and suggest that it might be possible to pharmacologically produce further increases in the rate of resolution of this form of edema.