이 연구는 자연발생고혈압쥐(SHR)의 혈압, 골격근에서의 혈관생성 및 혈관내피세포성장인자 발현(VEGF)에 미치는 지구성운동의 효과를 조사하였다. 5주령 SHR와 WKY는 무작위로 정상혈압군(WKY, Wistar-Kyoto rat, n=9), 고혈압통제군(SHR-C, SHR Control, n=9) 및 고혈압운동군(SHR-E, SHR Exercise, n=9)으로 각각 분류하였고, 지구성운동은 트레드밀을 이용하였다(12-20 m/min, 0% grade, 60 min/day, 5 days/wk, 16 wk). 수축기혈압은 지구성운동에 의해 효과적으로 감소되었다(SHR-E vs. SHR-C, $p$ <0.05). 골격근의 모세혈관밀도와 VEGF 단백발현은 고혈압통제군(SHR-C)이 정상혈압군(WKY)보다 모두 감소되었으나, 지구성운동(SHR-E)이 고혈압통제군(SHR-C)에 비해 모두 증가되었다. 이러한 결과들은 지구력운동 트레이닝이 SHR 골격근의 VEGF 단백발현의 증가를 통해 모세혈관밀도를 향상시키고, 이러한 모세혈관밀도의 향상이 SHR의 혈압상승을 억제할 수 있다는 것을 의미한다.
This study investigated the effect of endurance exercises on blood pressure, angiogenesis, and the vascular endothelial growth factor (VEGF) expression in the skeletal muscle of spontaneously hypertensive rats (SHR). Five week old SHRs and Wistar-Kyoto rats (WKY) were randomly divided into 3 groups: Wistar-Kyoto rats (WKY, n=9), SHR control (SHR-C, n=9), and SHR endurance exercise training (SHR-E, n=9). Endurance exercise training was performed on a treadmill (12-20 m/min, 0% grade, 60 min/day, 5 days/week, 16 weeks). Systolic blood pressure was monitored with the tail-cuff method. The expression of VEGF protein and capillary density were identified using western blotting and H&E staining in the soleus muscle, respectively. Systolic blood pressure was reduced by endurance exercise in SHR ($p$ <0.05). The capillary density of skeletal muscles in SHR-C was lower than in WKY ($p$ <0.05), but it was recovered by endurance exercise training (SHR-E) compared to SHR-C ($p$ <0.05), and VEGF protein was also increased by endurance exercise training compared to SHR-C ($p$ <0.05). These data suggest that the enhancement of capillary density via an increase of VEGF expression in skeletal muscles by endurance exercise training could be an important factor to inhibit blood pressure elevation in SHR.
