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目的探讨犬急性心功能不全状态下肾动脉血流和肾微血管床血流灌注的改变及血管紧张素转换酶抑制剂对其影响。方法12只杂种犬,结扎冠状动脉前降支并快速右室起搏,制作急性心功能不全模型,同时开腹暴露左侧肾脏及肾动脉,应用多普勒血流探测仪监测升主动脉根部血流量(心输出量,CO)和肾动脉血流量(RBF)。在基础及CO下降25%(LCO25%)和50%(LCO50%)时,观察CO和RBF改变。同时进行肾脏对比超声检查,测定肾微血管血流速度(β)、微血管容积(A)和微血管血流量(A×β)。在LCO50%后给予卡托普利1mg/kg及2mg/kg静脉注射,并在注射前后重复完成CO、RBF和肾对比超声检测。结果基础状态下,CO、RBF、肾皮质β、A和A×β值分别为(1·46±0·16)ml/min、(107·5±35·7)ml/min、1·39±0·14、120·3±14·8和167·4±25·0。当LCO25%和LCO50%时,RAF、肾皮质β、A和A×β值分别减至(72·50±32·4)ml/min、0·87±0·082、117·6±13·1、102·6±15·5和(44·1±17·2)ml/min、0·61±0·039、106·9±12·0、64·7±8·83。表明在LCO25%时,随CO和RBF的下降,肾皮质微血管床血流灌注即减少(A×β减少,P<0·05),其中以β减少为主,A无明显变化。当LCO50%时,肾动脉和肾微血管床血流灌注进一步下降,此时肾皮质血管床容积亦减少(与LCO25%比较,P<0·05)。在LCO50%时,应用卡托普利1mg/kg和2mg/kg后,平均动脉压由(85·4±7·8)mmHg(1mmHg=0·133kPa)降低至(78·7±7·3)mmHg和(69·1±6·3)mmHg(P<0·05);CO由0·73±0·084增至0·83±0·065和0·9±0·054(P<0·05);RBF由(44·1±17·2)ml/min增至(60·3±17·8)ml/min和(79·4±17·8)ml/min(P<0·05)。两种剂量的卡托普利使CO增加的比值分别为0·15±0·084和0·31±0·0111,而RBF增加的比值分别为0·290±0·089和0·522±0·040,均显著大于CO的增加比值。与此同时,卡托普利1mg/kg和2mg/kg使肾皮质β由0·61±0·039增至0·75±0·020和0·86±0·027;A由106·9±11·9增至115·4±11·1和116·6±8·9;A×β由64·7±8·83增至87·0±8·6和100·6±8·9。结论在急性心功能不全伴肾功能衰竭的情况下,应用加强肾微循环血流灌注的治疗措施可能有益于肾功能及心功能的恢复。
Objective To investigate the changes of renal arterial blood flow and renal microvascular bed blood perfusion in dogs with acute cardiac insufficiency and the effect of angiotensin converting enzyme inhibitors on it. Methods Twelve dogs were used to ligate the anterior descending branch of coronary artery and rapid right ventricular pacing to make the model of acute cardiac insufficiency. At the same time, the left kidney and renal artery were exposed by laparotomy. The ascending aorta root was monitored by Doppler flow detector Blood flow (cardiac output, CO) and renal artery blood flow (RBF). Changes in CO and RBF were observed at basal and CO declines of 25% (LCO 25%) and 50% (LCO 50%). Simultaneous renal contrast ultrasound examination, renal microvascular flow velocity (β), microvessel volume (A) and microvascular blood flow (A × β). Captopril at 1 and 2 mg / kg was given intravenously after 50% of LCO, and CO, RBF and renal contrast ultrasound were repeated before and after LCO. Results Under the basal condition, the β, A and A × β values of CO, RBF and renal cortex were (1.46 ± 0.16) ml / min, (107.5 ± 35.7) ml / min and 1.39 ± 0 · 14, 120 · 3 ± 14 · 8 and 167 · 4 ± 25 · 0. When LCO25% and LCO50%, the values of β, A and A × β in renal cortex decreased to (72 · 50 ± 32 · 4) ml / min, 0.87 ± 0.082 and 117 · 6 ± 13 · 1,102 · 6 ± 15 · 5 and (44 · 1 ± 17 · 2) ml / min, 0 · 61 ± 0 · 039, 106 · 9 ± 12 · 0 and 64 · 7 ± 8 · 83 respectively. The results showed that with the decrease of CO and RBF at 25% LCO, the perfusion of renal cortex microvascular bed was reduced (A × β, P <0 · 05), with the decrease of β, and no significant change of A. When LCO50%, renal artery and renal microvascular bed further decreased perfusion, renal cortical vascular bed volume also decreased (compared with 25% LCO, P <0. 05). Mean arterial pressure decreased from (85.4 ± 7.8) mmHg (1 mmHg = 0.133 kPa) to (78.7 ± 7.3)% at captopril 1 mg / kg and 2 mg / kg at LCO 50% ) mmHg and (69.1 ± 6.3) mmHg respectively (P <0.05); CO increased from 0.73 ± 0.084 to 0.083 ± 0.065 and 0.9 ± 0.054 (P < 0.05). The RBF increased from (44.1 ± 17.2) ml / min to (60.3 ± 17.8) ml / min and (79.4 ± 17.8) ml / min · 05). The ratios of increasing CO with two doses of captopril were 0 · 15 ± 0 · 084 and 0 · 31 ± 0 · 0111 respectively, while the ratios of increasing RBF were 0 · 290 ± 0 · 089 and 0 · 522 ± 0 · 040, were significantly greater than the increase of CO ratio. In the meantime, captopril at 1 mg / kg and 2 mg / kg increased renal cortex β from 0 · 61 ± 0 · 039 to 0 · 75 ± 0 · 020 and 0 · 86 ± 0 · 027; A was increased by 106 · 9 ± 11 · 9 to 115 · 4 ± 11 · 1 and 116 · 6 ± 8 · 9; A × β increased from 64 · 7 ± 8 · 83 to 87 · 0 ± 8 · 6 and 100 · 6 ± 8 · 9 . Conclusion In cases of acute cardiac dysfunction with renal failure, the application of therapeutic measures to enhance renal microcirculation perfusion may be beneficial to the recovery of renal function and cardiac function.