Abstract: Aim To study the effects of praeruptorin C (pra-C), a pure constituent isolated from "Qianhu", the roots of Peucedanum praeruptorum Dunn (Umbelliterae), on vascular hypertrophy, collagen content, transient [Ca²⁺]i, NO and vascular response of the thoracic aorta of renovascular and spontaneously hypertensive rats (RHR, SHR). Methods RHR were given pra-C 20 mg·kg^-1·d^-1 for 9 weeks, ig. Blood pressurs of both rats were measured using tail cuff manometry. Under inverted microscopy the length and width of the smooth muscle cells were measured by using computer software MICC (Dongnan University). [Ca²⁺]i of smooth muscle cells (SMCs) was measured with Fura-2/AM. By measuring the specific amino acid hydroxyproline content, the collagen content was obtained. By using Griess reagent, the NO in the SMCs was measured. Results The intermedium of the thoracic aorta in RHR was larger than that of the normal and pra-C-treated groups. The area (length×width) of the SMCs of thoracic aorta from RHR was 73.4 μm vs normal 34.5 μm and pra-C 34μm. The collagen content of thoracic aorta was 39 ± 6.8 % dry weight in RHR, while 26.5 ± 3% in normal and 25.6 ±1.1% in pra-C treated RHR. The resting [Ca²⁺]i of SMCs was (150±8), (226±11) and (362±18) nmol·L^-1 separately in normal rats, RHR and SHR. In the presence of KCl 60 mmol·L^-1, NE 10 μmol·L^-1, ANG II 100 nmol·L^-1 and ATP 30 μmol·L^-1, the [Ca²⁺]i of SMCs were increased by 128%; 132%; 233% and 152% in RHR, respectively. Similarly, 60 mmol·L^-1 KCl and 10 μmol·L-1 NE also increased the [Ca²⁺]i of SMCs by 235% and 200% in SHR. Pretreating with pra-C could decrease the level of [Ca²⁺]i to the normal level whether in RHR or in SHR. The amount of NO of SMCs was decreased 76% in SHR compared with normal group, while pra-C could recover this change. In addition, pra-C improved the vascular responses of thoracic aorta of RHR. Conclusion These results indicate that pra-C improved the vascular hypertrophy by decreasing the area of SMCs, collagen content, SMCs [Ca²⁺]i and increasing NO production.

Key words: Praeruptorin C, Praeruptorin C, Vascular smooth muscle hypertrophy, Vascular smooth muscle hypertrophy, Smooth muscle cells (SMCs)[Ca2+]i, Smooth muscle cells (SMCs)[Ca2+]i, NO, NO