Pulmonary responses to heparin-protamine complexes: the effects of age and species

To test the hypothesis that heparin-protamine complexes (H-P complexes) react with pulmonary intravascular macrophages, we studied the difference in the pulmonary reaction to H-P complexes between goats and rabbits and among different-aged goats. The increases in pulmonary arterial pressure (Ppa) and plasma thromboxane levels (Tx) after injection of H-P complexes (1.2 ml/kg) in goats (delta Ppa = 17 +/- 7.0 mmHg, delta Tx = 17.3 +/- 10.1 ng/ml) were significantly greater than in rabbits (delta Ppa = 0.50 +/- 1.0 mmHg, delta Tx = -0.01 +/- 0.17 ng/ml), the increase in Ppa in adult goats (> 150 days old; delta Ppa = 17 +/- 7.0 mmHg) was about sixfold higher than in newborn goats (1-3 days old; delta Ppa = 2.8 +/- 4.0 mmHg), and the increase in Tx in adult goats (delta Tx = 17.3 +/- 10.1 ng/ml) was significantly greater than those in newborn and young (19 days old) goats (delta Tx = 0.69 +/- 0.48 and 3.60 +/- 0.36 ng/ml, respectively). The pulmonary hemodynamic reaction to H-P complexes is consistent with the concept that the H-P complexes react with pulmonary intravascular macrophages.