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

当肾灌注压力改变时，肾脏表现出维持血流和肾小球滤过率恒定的能力。两个因素促成了这种自我调节反应，小管肾小球反馈和肌源性反应。此前，人们利用微穿刺技术研究肾脏的自动调节。在这项研究中，我们使用光谱分析（最大熵法、MEM和小波法）研究肾皮质血流，以确定一氧化氮和血管紧张素II在SHR中肾脏自动调节中的作用。方法：研究1。采用氯氯糖麻醉的17周龄雄性WKY/Izm、SHR/Izm和SHRSP/Izm。研究了NO合成抑制剂（L-NAME; 0.5、1.0 mg/kg）对肾脏的同动力学反应。采用激光多普勒血流仪测定肾皮质血流（RBF）。采用最大熵法对RBF变异性进行谱分析。TGF振荡（30-50mHz）用速尿确认。研究2。WKY/I…更多的zm和SHR/Izm使用。静脉注射血管紧张素II （Ang II; 5、15、50、100 ng/kg/min，静脉注射20 min）。采用小波分析方法对RBF进行分析。结果：(1)SHRSP患者左心室和主动脉重量增加。(2) WKY、SHR和SHRSP组的基线平均动脉压（MAP）分别为131±4、182±3和214±3 mmHg。WKY、SHR和SHRSP的基线RBF分别为49±1、39±2和36±1 ml/min/100g。L-NAME增加MAP，降低RBF。(3) L-NAME显著增加了TGF在WKY和SHR中的振荡，但对SHRSP没有影响。(4)小波可以在5秒内同时分析RBF， Ang II在两个菌株中都有增加TGF振荡的趋势。与传统的基于MEM的谱图方法相比，小波分析具有更好的时频分辨率。结论：小管肾小球反馈反应在SHRSP中减弱。在SHRSP中，一氧化氮在TGF中不起主要作用。这种TGF紊乱可能受到靶器官损伤的影响。这些结果表明，在SHRSP中，一氧化氮对肾脏自动调节的作用受到损害。小波法提高了分析的分辨率，可作为大鼠TGF振荡的一般指标。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