Pulmonary Endothelial Cells and the Metabolism of Adenine. Nucleotides, Kinins and Angiotensin I
As indicated in previous publications (1–9) and as revealed in the preceding paper (10), it is likely that circulating adenine nucleotides, kinins and angiotensin I are metabolized by enzymes of the luminal surface of the pulmonary endothelium. One of the nucleotides, namely adenosine-5’-monophosphate (AMP), is metabolized by enzymes of caveolae intracellulares open to the vascular lumen (7–9). This enzymic activity is not peculiar to those caveolae open to the vascular lumen, as one can show by reactions performed on fixed blocks of tissue (5,6) that other caveolae and intracellular vesicles are capable of degrading nucleotides. However, in the case of metabolism of circulating nucleotides it appears that only those caveolae open to the lumen have access to the substrate.
KeywordsAdenine Nucleotide Luminal Surface Vasoactive Substance Vascular Lumen Lead Phosphate
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