Abstract
In patients with spontaneous pneumothorax, the possibility of the involvement of plasma kallikrein-kinin system during reexpansion was examined, since bradykinin (BK) is potent in vasodilatation and vascular permeability increase and BK released initiates the onset of pulmonary circulation in the neonate at birth. Prekallikrein (PKK), high molecular weight and low molecular weight kininogens (HMWK and LMWK), precursors of BK, in plasma and other parameters of eleven patients were compared with those of seven normal control subjects. After reexpansion, increase in hematocrit and decrease in plasma protein concentration were observed in 9 of 11 patients (p<0.05 and p<0.01, respectively). Pulse pressure was also significantly increased. The plasma level of HMWK was 11.3±1.5 (mean±SD)ngBKeq./mg protein before reexpansion and was not different from that of the normal control subjects, but all of these levels of the individual patients were significantly reduced after reexpansion (p<0.001). Furthermore, the reduction of HMWK (1.27±0.7 [n=7] vs 0.55±0.2ngBKeq./mg protein [n=4]) was significantly larger in the cases of longer duration in the lung collapse (three days or longer), compared with those of shorter duration (less than three days). Significant increase in hematocrit was also observed in the former group by paired t-test, whereas the increase was not different from zero in the latter group. These findings suggest that BK may be released during reexpansion and cause hematocrit increase and vasodilatation, particularly in cases of longer duration of lung collapse.
