EFFECTS OF THE ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR ENALAPRIL ON BLOOD HEMATOPOIETIC PROGENITORS AND ACETYL-N-SER-ASP-LYS-PRO CONCENTRATIONS

Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) is a physiological inhibitor of the proliferation of haematopoietic stem cells. In 12 healthy volunteers t reated with the angiotensin-converting enzyme (ACE) inhibitor enalapri l (20 mg day(-1) for 15 days), we studied plasma and urinary AcSDKP le vels, the in vitro degradation of AcSDKP by plasma ACE and the numbers of circulating haematopoietic progenitors (granulocyte-monocytic colo ny forming unit: CFU-GM; bust forming unit-erythroid: BFU-E; and mixed colony forming unit: CFU-mixed). During treatment, plasma and urinary AcSDKP concentrations increased 2- to 5-fold, degradation of AcSDKP w as reduced, and CFU-mixed significantly increased by 100% while BFU-E and CFU-GM significantly decreased by 16% and 26%, respectively. These results indicate that ACE inhibitors may be of value during chemother apy or radiotherapy, warranting further study.