血漿Calcitonin Gene-Related Peptide(CGRP)のRadioimmunoassayに関する検討とその臨床応用

概要

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Recently, it has been recognized that a potent vasodilating peptide, calcitonin generelated peptide (CGRP), is widely distributed in the endocrine and nervous systems and detected in circulating blood in both rats and healthy men. However, the physiological and pathophysiological roles of CGRP in cardiovascular disease are still unknown. In this study, therefore, in order to clarify the physiological and pathophysiological roles of CGRP in normotensives (NT), essential hypertensives (EHT) and patients with chronic renal failure (CRF), a sensitive radioimmunoassay (RIA) for the determination of CGRP in human plasma was established and plasma CGRP levels were evaluated in these diseases. Synthetic CGRP, 125I-His CGRP and anti-CGRP antiserum were used in this RIA system. The bound form of 125I-His CGRP to antibody was separated from the free form using the second antibody polyethylene glycol method. The assay was able to detect as little as 2pg/tube of CGRP. The recovery of CGRP extracted by Sep Pak C-18 cartridge was 104±9.6%. The concentrated plasma and synthetic CGRP were applied to Sephadex G-75 column chromatography to determine CGRP immunoreactivity in each fraction. Synthetic CGRP showed one sharp peak of immunoreactivity, while plasma samples showed a second peak in an earlier fraction of the chromatography in addition to the same peak as the synthesic CGRP. Furthermore, CGRP levels in unextracted samples were markedly higher than those in extracted samples. Thus, it was confirmed that the extraction procedure is necessary to determine the human plasma CGRP level. Plasma CGRP levels determined by our assay system in NT (n=30:18.2±1.3pg/ml) were apparently lower than those reported previously from other laboratories, in which unextracted plasma samples had been measured. On the other hand, CGRP levels were significantly higher in EHT (n=16:31.2±3.9pg/ml) and CRF (n=8:43.4±4.6pg/ml) than those in NT. After hemodyalysis (HD), CGRP levels significantly decreased in CRF. CGRP immunoreactivity was identified in the filtered solution obtained by the extracorporeal ultrafiltration method (ECUM). Therefore, the higher CGRP levels in CRF might be caused at least partly by decreased excretion of immunoreactive CGRP from the kidney. The decrease of CGRP by HD may be explained at least partly by its removal by the dialyzer membrane. Regarding the pathophysiological significance of increased plasma CGRP levels, since these are elevated in EHT, it is unlikely that this peptide plays an important role in the etiology of essential hypertension. The increase of plasma CGRP levels in EHT should be considered as a secondary and compensatory reaction to elevated blood pressure. Further study is necessary t?o clarify the mechanism, that caused the increase of CGRP in EHT.
札幌医科大学の論文
1990-10-01

血漿Calcitonin Gene-Related Peptide(CGRP)のRadioimmunoassayに関する検討とその臨床応用

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概要

札幌医科大学 | 論文

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