Abstract: AIM: To determine whether CRP is rele-vant to pathological arterial smooth muscle and to investi-gate both aorta and carotid arteries response to CRP in LDLr(-/-), eNOS(-/-) and db/db(+/ ?) mice arteries.METHODS: CRP was added in these kinds of arterial rings in order to check arterial tension response. Tension was recorded in isolated rings of aorta and carotid arteries taken from low-density lipoprotein receptor gene knockout mice, endothelial nitric oxide synthase knockout mice (eNOS(-/-) mice), diabetes mellitus mice (db/db+/ ? mice) and the corresponding wild -type strain.RE-SULTS:CRP relaxed aorta and carotid artery by phenyle-phine or prostaglandin F2α(PGF 2α) in normal mice, LDLr(-/-), eNOS(-/-) and db/db(+/ ?) mice.CRP relaxed aorta to (90±2) %and carotid to (54±3) %in LDLr(-/-), aorta to (74 ±2) % and carotid to (38 ± 4) %in eNOS, aorta to (47±6) %and carotid to (52± 8) % in db/db(+/ ?), and aorta to (66 ±8) % and carotid (32 ±4) %in normal mice. CRP-induced vessel dilation was abolished in carotid impaired endothelium, but not in aorta. CRP relaxed aorta, and carotid in LDLr (-/-) mice better than others.CRP only relaxed (9 ± 4) %in carotid endothelium damaged and relaxed (58± 4) % in aorta endothelium damaged. CONCLUSION: CRP is a very strong vascular muscle relaxation similar to NO.Its effect time is similar to that in NO. It is similar to normal mice arteries in CRP relaxing aorta and carotid, and independent of and depend on endothelium to dilate artery smooth muscle.

Key words: CRP, carotid, aorta, LDLr, db/db (+/ ?), eNOS