Investigations of Components of the Renin‐Angiotensin System in Rat Vascular Tissue
作者:
JULIAN ROSENTHAL,
BEATE PFEIFLE,
MICHAIL MICHAILOV,
JOHANNA PSCHORR,
INGRID JACOB,
HERBERT DAHLHEIM,
期刊:
Hypertension
(OVID Available online 1984)
卷期:
Volume 6,
issue 3
页码: 383-390
ISSN:0194-911X
年代: 1984
出版商: OVID
关键词: renin;angiotensin-I-converting enzyme;angiotensinases;rat aorta;rat vena cava
数据来源: OVID
摘要:
Investigations were performed on components of the renin-angiotensin system (RAS) in homogenate extracts of vascular tissue and aortic smooth muscle cells cultivated in vitro. Determinations of isoelectric points and pH optima indicated the existence in aortic homogenate extracts of two local angiotensin I (AI)-forming enzymes (AIFE) that were different from those of plasma, renal cortex, veins, and aortic smooth muscle cells. The pH optima for Al-converting enzyme (ACE) from vascular tissues, aortic smooth muscle cells, and plasma were in the same range (pH 8.0–8.5), and in agreement with those measured previously in other tissues. In contrast, in vitro studies with the ACE inhibitors MK-421 and MK-422 and measurement of isoelectric points suggested that aortic ACE was different from the plasma enzyme. AIFE and ACE activities were found to be elevated in spontaneously hypertensive rats (SHR). The biochemical characteristics of the enzymes investigated in the vascular tissue of SHR were not different from those of the normotensive controls. AI- and All-degrading enzymes were found both in aortic tissue and in aortic smooth muscle cells. One potent Al-degrading enzyme different from ACE was observed in aortic tissue. A high ratio of AI/AII immunoreactivities in arterial walls suggests the availability of renin substrate, and that Al-degrading enzymes are the rate-limiting enzymes for AH formation. The results further support the concept of an intrinsic vascular RAS.
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