C-TYPE NATRIURETIC PEPTIDE INHIBITS UPR EGULATION OF α1-ADRENOCEPTOR AND INOSITO L 1,4,5-TRISPHOSPHATE RECEPTOR IN RAT VASCULAR SMOOTH MUSCLE AFTER VASCULAR ENDOTHELIAL INJURY

Objective.In a model o f balloon injury of rat aortic endotheli um, the effects of C-type natriuretic pe ptide(CNP) on α1-adrenoreceptor and ino sitol 1,4,5-triphosphate (IP3) receptor were studied Methods. Aortic injuri es were produced by vascular endothelium -denudation.α1- adrenoreceptor in smoot h muscle sarcolemma and IP3 receptor in smooth muscle sarcoplasmic reticulum in the rat aorta were assayed by radioactiv e analysis method.Results. It was found that neointima was formed and the conten ts of DNA, collagen and elastin of each int ima-media were significantly increased i n 7 days and 21 days after balloon injury of rat aorta. α1-adrenoreceptor in smo oth muscle sarcolemma and IP3 receptor in sarcoplasmic reticulum were also upre gul ated. Results also showed that the admin i stration of CNP i.p significantly decrea sed the contents of DNA, collagen and el as tin of each intima-media, and inhibited the up-regulation of α1-adrenoreceptor and IP3 receptor.Conclusion. The inhibition of the up-regulation of α 1-adrenoreceptor and IP3 receptor by C NP might be one of the mechanisms of its suppressive action on intimal proliferation.