M. Sapijaszko et al., PROTEIN-KINASE-C ACTIVITY DURING THE PROCESS OF LUNG LIQUID CLEARANCE, The American journal of physiology, 265(1), 1993, pp. 120000057-120000066
Although active transport of sodium plays an important role in the res
olution of pulmonary edema, the biochemical regulation of this process
is still under investigation. The purpose of this study was to evalua
te the activity of protein kinase C during the process of lung liquid
clearance. Alveolar flooding was induced by instilling 5% bovine serum
albumin solution, saline, or heterologous serum in the air spaces of
rats. The activity of protein kinase C was measured in both the instil
led and control lungs at 10 min and 1 and 4 h after fluid instillation
. Four hours after instillation of 5% bovine serum albumin, the ratio
of protein kinase C activity in the instilled lung compared with the c
ontrol lung was 2.2 +/-0.3. Similar results were obtained following in
stillation with heterologous serum or saline. Since we measured a clea
rance rate of 0.8 ml/h in anesthetized rats, we can postulate that the
activation of protein kinase C occurred when >40% of the liquid had b
een cleared from the lung. This increased activity of protein kinase C
was not due to an increase in kinase activity in the inflammatory cel
ls or an increase in enzyme quantity but due to a decrease of protein
kinase C inhibitory activity in the lung. These results suggest that p
rotein kinase C second messenger system may play a regulatory role in
lung liquid clearance.