Spectral analysis of renal microcirculation in spontaneously hypertensive rat (SHR) using the new developed wavelet method

当肾脏灌流压力改变时，肾脏表现出维持血流和肾小球滤过率恒定的能力。有两个因素参与了这种自我调节反应，即肾小球反馈和肌源性反应。在此之前，肾脏的自我调节是用微穿刺法研究的。在本研究中，我们利用频谱分析(最大熵法、MEM法和小波法)研究了一氧化氮和血管紧张素II在SHR肾脏自身调节中的作用。方法：研究1.采用氯醛糖麻醉的雄性WKY/IZM、SHR/IZM和SHRSP/IZM(17周龄)。本文研究了NO合成抑制剂(L-NAME，0.5，1.0 mg/kg ia)对肾脏血流动力学的影响。用激光多普勒血流仪测定肾皮质血流量(RBF)。利用最大熵方法对径向基函数的变异性进行了谱分析。用速尿证实了转化生长因子的振荡(30-50 MHz)。研究2.WKY/I…更多使用ZM和SHR/IZM。血管紧张素II(Ang II；5、15、50、100 ng/kg/min，静脉注射20min)。结果：(1)SHRSP患者左心室和主动脉重量增加。(2)基础平均动脉压(MAP)：WKY组为131±4，SHR组为182±3，SHRSP组为214±3。基础RBF：WKY组49±1，SHR组39±2，SHRSP组36±1ml/min/100g。L-NAME升高MAP，降低RBF。(3)L-NAME显著增加WKY和SHR的转化生长因子振荡，但对SHRSP无明显影响。(4)小波每隔5s即可同时分析RBF。血管紧张素转换酶II在两个菌株中都有增加转化生长因子振荡的趋势。与传统的基于MEM的频谱分析方法相比，小波分析具有更好的时频分辨率。结论：SHRSP患者的肾小管球反馈反应减弱。一氧化氮在SHRSP的转化生长因子中不起主要作用。这种转化生长因子的紊乱可能与靶器官损伤有关。这些结果提示，SHRSP时，NO对肾脏自身调节的作用受损。小波分析方法提高了分析分辨率，可作为大鼠转化生长因子振荡的一般指标。较少

The kidney exhibits an ability to maintain the blood flow and glomerular filtration rate constant when the renal perfusion pressure is altered. Two factors contribute to this autoregulatory response, tubuloglomerular feedback and myogenic response.Previously, the renal autoregulation was studied using the micropuncture technique. In this study, we investigated the renal cortical blood flow using the spectral analysis (Maximum entropy method; MEM and Wavelet method) to determine the role of nitric oxide and angiotensin II on the renal autoregulation in SHR.Methods: Study 1. The chloralose-anesthetized male WKY/Izm, SHR/Izm and SHRSP/Izm (17 weeks old) were used. Renal homodynamic responses to NO synthesis inhibitor (L-NAME; 0.5, 1.0 mg/kg ia) were studied. Renal cortical blood flow (RBF) was measured by the laser-Doppler flowmeter. The spectral analysis of RBF variability was performed using maximum entropy method. TGF oscillations (30-50mHz) were confirmed by furosemide. Study 2. WKY/I … More zm and SHR/Izm were used. Angiotensin II (Ang II; 5, 15, 50, 100 ng/kg/min, 20-min iv) was infused. RBF was analyzed by Wavelet method.Results: (1) Left ventricle and aorta weights were increased in SHRSP. (2) Baseline mean arterial pressure (MAP) was 131±4, 182±3 and 214±3 mmHg in WKY, SHR and SHRSP, respectively. Baseline RBF was 49±1, 39±2, and 36±1 ml/min/100g in WKY, SHR and SHRSP, respectively. L-NAME increased MAP and decreased RBF. (3) L-NAME significantly increased TGF oscillations in WKY and SHR, but did not affect in SHRSP. (4) Wavelet could analyze RBF simultaneously ever 5 sec. Ang II tended to increased TGF oscillations in both strains. Compared with conventional spectrogram approach based on MEM, wavelet analysis yields a better time-frequency resolution.Conclusions: Tubuloglomerular feedback response was attenuated in SHRSP. Nitric oxide did not play a major role in TGF in SHRSP. This disorder of TGF might be affected by target organ damage. These results suggest that the effects of Nitric oxide on renal autoregulation are impaired in SHRSP. Wavelet method provides improved resolution of analysis and can be used as general indexes of TGF oscillations in rats. Less