Ahmeda Ahmad F, Rae Mark G, Al Otaibi Mohammed F, Anweigi Lamyia M, Johns Edward J
Department of Physiology, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
Department of Physiology, University College Cork, Cork, Republic of, Ireland.
J Physiol Biochem. 2017 May;73(2):207-214. doi: 10.1007/s13105-016-0541-1. Epub 2016 Dec 9.
Vasoconstriction within the renal medulla contributes to the development of hypertension. This study investigated the role of reactive oxygen species (ROS) in regulating renal medullary and cortical blood perfusion (MBP and CBP respectively) in both stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar rats. CBP and MBP were measured using a laser-Doppler flow meter before and after intra-renal infusion of tempol, the superoxide dismutase (SOD) mimetic or tempol plus catalase, the hydrogen peroxide-degrading enzyme. Tempol infusion significantly elevated blood perfusion within the renal medulla (MBP) in both SHRSP (by 43 ± 7%, P < 0.001) and Wistar rats (by 17 ± 2%, P < 0.05) but the magnitude of the increase was significantly greater in the SHRSP (P < 0.01). When the enzyme catalase and tempol were co-infused, MBP was again significantly increased in SHRSP (by 57 ± 6%, P < 0.001) and Wistar rats (by 33 ± 6%, P < 0.001), with a significantly greater increase in perfusion being induced in the SHRSP relative to the Wistar rats (P < 0.01). Notably, this increase was significantly greater than in those animals infused with tempol alone (P < 0.01). These results suggest that ROS plays a proportionally greater role in reducing renal vascular compliance, particularly within the renal medulla, in normotensive and hypertensive animals, with effects being greater in the hypertensive animals. This supports the hypothesis that SHRSP renal vasculature might be subjected to elevated level of oxidative stress relative to normotensive animals.
肾髓质内的血管收缩会促使高血压的发展。本研究调查了活性氧（ROS）在调节易中风自发性高血压大鼠（SHRSP）和Wistar大鼠的肾髓质及皮质血流灌注（分别为MBP和CBP）中的作用。在肾内输注超氧化物歧化酶（SOD）模拟物tempol或tempol加过氧化氢降解酶过氧化氢酶之前和之后，使用激光多普勒血流仪测量CBP和MBP。输注tempol可使SHRSP（升高43±7%，P<0.001）和Wistar大鼠（升高17±2%，P<0.05）的肾髓质内血流灌注（MBP）显著升高，但SHRSP中升高的幅度显著更大（P<0.01）。当同时输注酶过氧化氢酶和tempol时，SHRSP（升高57±6%，P<0.001）和Wistar大鼠（升高33±6%，P<0.001）的MBP再次显著升高，相对于Wistar大鼠，SHRSP中诱导的灌注升高显著更大（P<0.01）。值得注意的是，这种升高显著大于单独输注tempol的动物（P<0.01）。这些结果表明，在正常血压和高血压动物中，ROS在降低肾血管顺应性方面发挥着更大的作用，尤其是在肾髓质内，在高血压动物中的作用更大。这支持了以下假设：相对于正常血压动物，SHRSP的肾血管系统可能受到更高水平的氧化应激。
