Our long-term goal is to help clarify how the lungs regulate the peptide hormone composition of systemic arterial blood. In the present project, our goal is to evaluate pulmonary aminopeptidase P in terms of its ability to react with intravascular substrates, in particular with bradykinin. At present, little is known about aminopeptidase P in general and pulmonary aminopeptidase P in particular. Thus, our specific aims are 1) to purify and characterize aminopeptidase P of rat lungs; 2) to prepare monoclonal and polyclonal antibodies against the enzyme and then use the antibodies to clarify the cellular and subcellular sites of aminopeptidase P within the lungs; and 3) to examine the ability of aminopeptidase P of intact rat lungs to process bradykinin and a new synthetic substrate, Arg-Pro-Pro-(3H)benzylamide, presented by central venous blood. By so proceeding, we expect to help clarify an enzymic mechanisms by which the lungs prevent bradykinin from entering systemic arterial blood. The information thus obtained should improve understanding of a previously unrecognized non-ventilatory function of the lungs. In addition to the intrinsic interest of learning how the lungs regulate certain peptide hormone systems, our finding may have clinical implications. The lungs are known to contain another enzyme, angiotensin converting enzyme (ACE; a.k.a. kininase II), capable of inactivating bradykinin. Inhibitors of ACE are now used commonly in the treatment of hypertension and congestive heart failure. By clarifying interactions of pulmonary aminopeptidase P with circulating bradykinin, we amy obtain new insights into how systemic arterial blood concentrations of bradykinin are controlled when ACE is fully inhibited.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL039684-03
Application #
3356503
Study Section
Biochemistry Study Section (BIO)
Project Start
1988-09-30
Project End
1991-09-29
Budget Start
1990-09-30
Budget End
1991-09-29
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Miami School of Medicine
Department
Type
Schools of Medicine
DUNS #
City
Miami
State
FL
Country
United States
Zip Code
33146
Denslow, N D; Ryan, J W; Nguyen, H P (1994) Guinea pig membrane-bound aminopeptidase P is a member of the proline peptidase family. Biochem Biophys Res Commun 205:1790-5
Ryan, J W; Berryer, P; Chung, A Y et al. (1994) Characterization of rat pulmonary vascular aminopeptidase P in vivo: role in the inactivation of bradykinin. J Pharmacol Exp Ther 269:941-7
Ryan, J W; Denslow, N D; Greenwald, J A et al. (1994) Immunoaffinity purifications of aminopeptidase P from guinea pig lungs, kidney and serum. Biochem Biophys Res Commun 205:1796-802
Ryan, J W; Chung, A Y; Berryer, P et al. (1992) A radioassay for aminoacylproline hydrolase (aminopeptidase P) activity. Biochim Biophys Acta 1119:133-9
Ryan, J W; Valido, F; Berryer, P et al. (1992) Purification and characterization of guinea pig serum aminoacylproline hydrolase (aminopeptidase P). Biochim Biophys Acta 1119:140-7
Chen, X; Orfanos, S E; Ryan, J W et al. (1991) Species variation in pulmonary endothelial aminopeptidase P activity. J Pharmacol Exp Ther 259:1301-7
Ryan, J W (1989) Peptidase enzymes of the pulmonary vascular surface. Am J Physiol 257:L53-60
Tseng, C J; Robertson, D; Light, R T et al. (1988) Neuropeptide Y is a vasoconstrictor of human coronary arteries. Am J Med Sci 296:11-6