Application of intravital fluorescence microscopy in the observation of the changes of hepatic microcirculation in rat with hepatic cirrhosis and portal hypertension / 中华消化外科杂志

Objective To investigate the value of intravital fluorescence microscopy in the observation of the changes of hepatic microcirculation in the rat model with hepatic cirrhosis and portal hypertension.Methods Seventy male SD rats were selected.According to the random number table,40 SD rats were randomly divided into the sham operation group,bile duct ligation (BDL) 2 weeks group,4 weeks group and 6 weeks group,there were 10 rats in each group,and the hepatic microcirculation of the rats was observed with intravital fluorescence microscope; the remaing 30 SD rats were randomly divided into the normal saline (NS) group,endothelin-1 (ET-1) group and the S-nitrosoglutathion (GSNO) group at 4 weeks later after the establishment of BDL model.The changes of hepatic microcirculation of the 3 groups were observed.All data were analyzed using the one-way analysis of variance (ANOVA) or paired samples t test.Results Nine rats died in the BDL model groups,and the survival rate was 85.0％ (51/60).All rats in the sham operation group were survived.The hepatic sinusoid diameters were decreased as time passed by.The hepatic sinusoid diameters of the BDL 2 weeks group,4 weeks group and 6 weeks group were (13.6 ± 1.0) μm,(8.8 ± 0.7) μm and (8.0 ± 0.5) μm,respectively,which were significantly shorter than (17.4 ± 1.0) μm of the sham operation group (t =5.86,18.24,15.57,P ＜ 0.05).The hepatic sinusoid densities of the BDL 2 weeks group,4 weeks group and 6 weeks group were (6.8 ±0.8)/ 200 μm,(4.3 ± 1.8)/200 μm and (4.0 ± 1.2)/200 μm,which were significandy lesser than (8.8 ± 0.5)/200 μm (t =3.25,2.77,2.12,P ＜ 0.05).At 15 minutes after injection of NS,the hepatic sinusoid diameter of the NS group was (7.2 ± 1.2) μm,which was significantly different from (6.9 ± 0.5) μm before injection of NS (t =0.89,P ＞ 0.05) ; the hepatic sinusoid density of the NS group before and after injection of NS were (6.6 ± 0.4) / 200 μm and (6.8 ± 1.4)/200 μm,with no significant difference(t =1.12,P ＞0.05).At 15 minutes after injection of ET-1,the hepatic sinusoid diameter of the ET-1 group was (5.4 ±0.5) μm,which was significantly different from (7.9 ± 0.6) μm before injection of ET-1 (t =7.39,P ＜ 0.05) ; the hepatic sinusoid density of the ET-1 group before and after ET-1 injection were (5.8 ± 1.2)/200 μm and (5.4 ± 1.8)/200 μm,with no significant difference(t =0.84,P ＞0.05).At 15 minutes after injection of the GSNO,the hepatic sinusoid diameter of the GSNO group was (11.4 ± 1.3) μm,which was significantly different from (7.5 ± 1.7) μm before injection of GSNO (t =5.95,P ＜ 0.05) ; the hepatic sinusoid density of the GSNO group before and after GSNO injection were(5.6 ± 0.8)/200 μm and (6.4 ± 1.6)/200 μm,with no significant difference (t =0.54,P ＞ 0.05).Conclusions The changes of hepatic microcirculation observed under intravital fluorescence microscope could reflect the progress of hepatic cirrhosis,and the changes of hepatic sinusoid diameters caused by drugs could be dynamically monitored under the intravital fluorescence microscope.

Changes of Hepatic Microcirculation Measured by Thermal Diffusion Probe after Vasopressor Infusion

PURPOSE: Various vasopressor agents are used to raise systemic vascular resistance (SVR) during liver transplantation. After grafted liver was reperfused, postreperfusion syndrome could be treated with various vasopressors. However, epinephrine can decrease the splanchnic perfusion and oxygen saturation and then hepatic blood flow would be jeopardized. Decreased hepatic blood flow might result in centrilobular necrosis which contributes to disruption of liver functions. We tried to know the effect of epinephrine on tissue perfusion of the liver. METHODS: In this study, measurement of hepatic microcirculation (HMC) and hemodynamic changes was performed in eight dogs to investigate the effect of vasopressors on hepatic microcirculation. Animals were divided into four groups in which low-dose epinephrine (0.05mug/Kg/min) and high-dose epinephrine (0.5mug/Kg/min) were randomly infused into the systemic vein and portal vein (1/6 of systemic dose) for ten minutes. Hepatic microcirculation was measured by Thermal Diffusion Probe. RESULTS: At low-dose systemic infusion of epinephrine, mean arterial bloodpressure (MABP), cardiac output (CO), and hepatic microcirculation (HMC) were significantly increased but systemic vascular resistance (SVR) was decreased. On high-dose epinephrine, MABP, CO (P=0.01), and SVR were significantly increased without changes of HMC. Intraportal infusion of low- and high-dose epinephrine increased hepatic vein pressure and SVR, respectively. CONCLUSION: These results would provide clues that systemic low-dose epinephrine infusion is enough to raise HMC and high-dose infusion of epinephrine to raise SVR could be used without jeopardizing HMC.

Response of Hepatic Microcirculation Following Hemodynamic Changes: An Experimental Study Using Laser Doppler Flowmetry in Dog

BACKGROUND: Management of a cadaveric donor with hemodynamic stability is essential for successful liver transplantation. Since the liver is susceptible to ischemic insult and since the blood pressure of a brain-dead patient is usually hypotensive, donor management should be performed on the bases of the hemodynamic characteristics of brain death and physiologic control of hepatic blood flow. In this study, the response of hepatic microcirculation was evaluated in six dogs in which hepatic innervation was sequentially altered and change of blood pressure and corresponding therapy for brain-dead donor was simulated. METHODS: The hepatic microcirculation in a dog model was measured by using laser Doppler flowmetry (LDF). Factors affecting the LDF signal were set as the mean arterial pressure (MAP), the central venous pressure (CVP), and the infusion of vasopressors. RESULTS: Common hemodynamic responses in dogs with innervated and sequentially denervated livers were as follows: First, buffering of the hepatic arterial flow was observed when the MAP was in the range of 60-120 mmHg. Second, a CVP of upto 12-13 cm saline did not decrease the LDF signal. Third, dopamine and dobutamine doses of up to 20 microgram/Kg/min offset the prehepatic flow resistance with elevation of the MAP against splanchnic vasoconstriction. Attenuation of hepatic arterial buffering was the only difference following hepatic denervation. Meanwhile, hepatic arterial buffering seemed not to be working when the MAP fell below 60 mmHg. CONCLUSIONS: Although dysfunction of the hepatic nerve in a brain-dead condition has not been evaluated, common responses from an innervated and sequentially denervated liver may be observed inthe livers of donors in a brain-dead state. The results of this experiment suggest that there is a certain control mechanism for hepatic blood flow, independent of hepatic innervation. Even though these results cannot be applied directly to clinical treatment, they will would provide clues about the control mechanism for hepatic blood flow for the management of brain-dead liver donors.