OBJECTIVETo study the modulatory effect of sulfur dioxide (SO(2)) on the accumulation of collagen type I and type III in the wall of aorta during spontaneously hypertensive rat (SHR) vascular remodeling.

METHODSEight male Wistar Kyoto rats at the age of 4 weeks with normal blood pressure were used as a control group. And sixteen male SHRs at the age of 4 weeks were randomly divided into an SHR control group and SHR + Na(2)SO(3)/NaHSO(3) (SO(2) donor) group. Na(2)SO(3)/NaHSO(3) solution was injected intraperitoneally everyday to the rats in the SHR + Na(2)SO(3)/NaHSO(3) group. After 5 weeks, the systemic blood pressure was measured. The weight ratio of left ventricle to the whole heart was also measured. The rat aorta was dyed with Hart's method. The morphometric parameters including outer radius, lumen radius and the wall thickness were calculated by Leica workstation. The plasma level of SO(2) was determined by HPLC method. The expressions of collagen type I and type III in aorta were detected by immunohistochemistry.

RESULTS(1) Compared with the WKY rat control group, the systolic blood pressure increased by 53%, the weight ratio of left ventricle to the whole heart increased by 6% but the plasma level of SO(2) decreased by 44% for rats in the SHR group (P < 0.01 or P < 0.05). Compared with the SHR control group, the systolic blood pressure decreased by 26%, but the plasma level of SO(2) increased by 28% (all P < 0.01) for rats in the SHR + Na(2)SO(3)/NaHSO(3) group. (2) Compared with the WKY rats, the ratio of media to lumen radius increased by 28% for SHR. Compared with the SHR group, the ratio of media to lumen radius decreased by 10% (P < 0.01) in rats of the SHR + Na(2)SO(3)/NaHSO(3) group. (3) Compared with rats in the WKY control group, collagen type I expression increased by 10% for rats in the SHR group (P < 0.01). Compared with the SHR group, however, the expression decreased by 58% for rats in the SHR + Na(2)SO(3)/NaHSO(3) group (P < 0.01). (4) Compared with rats in the WKY control group, the expression increased by 13% for rats in the hypoxia SHR group (P < 0.01); however, compared with rats in the SHR group, the expression decreased by 8% in the rats of the SHR +Na(2)SO(3)/NaHSO(3) group (P < 0.01).

CONCLUSIONSIn the process of SHR vascular collagen remodeling in the rats, SO(2) could inhibit the abnormal accumulation of collagen type I and type III in the wall of aorta. This effect may be one of the mechanisms by which SO(2) ameliorates SHR vascular remodeling.