Metabolism of endothelin-1 and big endothelin-1 by recombinant neutral endopeptidase EC.220.127.116.11
Hypertension-Endocrine Branch, NHLBI, National Institutes of Health, Building 10, Room 8C103, 9000 Rockville Pike, Bethesda, MD 20892, U.S.A.
- 1Inhibitors of neutral endopeptidase EC.18.104.22.168 (NEP) have been shown to attenuate the hypertensive effect of big-endothelin-1 (BET-1) in rats. To determine whether NEP converts BET-1 to endothelin-1 (ET-1), the effect of a recombinant NEP (rNEP) on BET-1 and on ET-1 was assessed in vitro.
- 2Incubation of [125I]-ET-1 with 1 μg ml−1 of rNEP resulted in degradation of the peptide within minutes. Increase in the amount of rNEP to 10 μg ml−1 led to total cleavage of [125I]-ET-1 within seconds.
- 3Phosphoramidon (10 μm) or SQ-28,603 (100 μm) totally suppressed the degradation of [125I]-ET-1 by rNEP.
- 4The degradation of [125I]-BET-1 by either 1 or 10 μg ml−1 of rNEP was much slower than that of [125I]-ET-1. Again, both phosphoramidon and SQ 28,603 protected the peptide from degradation.
- 5Intact [125I]-ET-1 was not observed when [125I]-BET-1 was incubated with rNEP.
- 6These data show that neutral endopeptidase EC.22.214.171.124 is not an endothelin converting enzyme.