Vasoconstrictor Responses After Neo-Intima Formation and Endothelial Removal In the Rabbit Carotid-Artery
Küçük Resim Yok
Tarih
1994
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Stockton Press
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
1 The present study examined the responses of the rabbit carotid artery to five vasoconstrictors after neo-intima formation induced by perivascular collar treatment and evaluated the role of constitutive and inducible nitric oxide (NO) synthase and endothelial cells (ECs). 2 Ring segments of the rabbit carotid artery were mounted in organ chambers for isometric tension recording. Neo-intima-bearing vessels developed less force (E(max)) in response to KCl, the thromboxane-mimetic U-46619 and 5-hydroxytryptamine (5-HT), but not to angiotensin I and II. 3 The collar-treatment increased the sensitivity to 5-HT, and decreased the sensitivity to angiotensin II. The sensitivity to U-46619 and angiotensin I remained unchanged. 4 Mechanical removal of ECs and inhibition of NO biosynthesis by N-G-monomethyl-L-arginine (L-NMMA) and N-G-nitro-L-arginine (L-NOARG) increased the sensitivity to 5-HT in sham and collar-treated segments to the same extent. The effects of collar-treatment and endothelial removal or treatment with inhibitors of NO biosynthesis were additive. Inhibition of NO biosynthesis failed to augment sensitivity to 5-HT after endothelial denudation. L-NOARG increased the force development to KCl in sham and collar-treated segments to the same extent. However, L-NMMA and L-NOARG failed to augment the contractile responses of neo-intima-bearing vessels to 5-HT and KCl after endothelial removal. 5 The responses to angiotensin I were not altered, either by the neo-intima or by endothelial removal. In arteries with a neo-intima the sensitivity to angiotensin II was decreased. Removal of the endothelium or incubation with L-NOARG counteracted this rightward shift and increased E(max). 6 Our results demonstrate that contractions to 5-HT, angiotensin II and KCl are modulated by NO in both sham and neo-intima-bearing vessels. Inhibition of NO biosynthesis and collar treatment resulted in additive effects on the EC(50) values, suggesting that the 5-HT and angiotension (AT) receptors on the smooth muscle cells are also modified by the formation of a neo-intima. Furthermore, the reduced contractile responses of segments with a neo-intima are not due to NO formed by an inducible NO synthase in those vessels.
Açıklama
Anahtar Kelimeler
NITRIC OXIDE, INDUCIBLE NITRIC OXIDE SYNTHASE (INOS), ENDOTHELIUM, NEO-INTIMA, 5-HT, ANGIOTENSIN, U-46619, POTASSIUM CHLORIDE, SILICONE COLLAR
Kaynak
British Journal of Pharmacology
WoS Q Değeri
N/A
Scopus Q Değeri
Cilt
112
Sayı
2
