Arterial resistance to neoplastic invasion

The relevance of proteinase inhibitors to the resistance of arterial walls against neoplastic invasion was investigated in human and porcine vessels using plasminogen activators as model. No significant differences in the inhibitory potential of extracts from the vascular walls were found between pulmonary and systemic arteries. It is concluded that the proteinase - inhibitor system studied is not responsible for the immunity of arterial walls against neoplastic invasion. The lack of antineoplastic resistance of pulmonary arteries may be explained by lesser intraarterial blood pressure and hence a lower pressure gradient across the vessel wall in pulmonary as opposed to systemic arteries.