Evolution of portal hypertension and mechanisms involved in its maintenance in a rat model

Simulation of prehepatic portal hypertension and impact of hepatic deportalization on its tissue

Objective. On the prehepatic portal hypertension pattern, created by partial ligature of venae portae in rats, to estimate the impact of partial hepatic deportalization on its tissue. Materials and methods. The investigation was conducted on 35 male rats of a Wistar line, aged 4–6 weeks. In 15 laboratory animals the partial ligature of vena porta with formation of stenosis was conducted, and in 15 –false ligature, while the control group consisted of 5 intact laboratory animals. Results. There were revealed certain connections between conduction of partial ligature of vena porta and critical (lethal) lowering of portohepatic perfusion. The model of prehepatic portal hypertension, using partial ligature of vena porta, leading to partial lowering of portohepatic perfusion with development of cavernous transformation of vena porta and dystrophic changes in hepatocytes with further fibrous changes in hepatic parenchyma, was applied. Conclusion. The portal vein narrowing grade in range 52 – 59% constitutes the optimal one for the prehepatic portal hypertension formation with development of zonal adipose parenchymatous hepatic dystrophy and the balloon degeneration of hepatocytes with further development of fibroses in rats of a Wistar line aged 4 – 6 weeks.

Pentadecapeptide BPC 157 resolves Pringle maneuver in rats, both ischemia and reperfusion

BACKGROUND

The Pringle maneuver [portal triad obstruction(PTO)] provides huge disturbances during ischemia and even more thereafter in reperfusion. Contrarily, a possible solution may be stable gastric pentadecapeptide BPC 157, with already documented beneficial effects in ischemia/reperfusion conditions. Recently, BPC 157, as a cytoprotective agent, successfully resolved vessel occlusions in rats (ischemic colitis; deep vein thrombosis, superior anterior pancreaticoduodenal vein; bile duct cirrhosis) through rapid collateral vessel recruitment to circumvent vessel occlusion. Thereby, medication BPC 157 regimens were administered as a single challenge before and during ischemia or, alternatively, at various time points during reperfusion.

AIM

To introduce BPC 157 therapy against pringle maneuver-damage.

METHODS

In deeply anesthetised rats, the portal triad was clamped up for 30 min. Rats then underwent reperfusion for either 15 min or 24 h. Medication [(10 µg, 10 ng/kg) regimens, administered as a single challenge] picked (a) ischemia, PTO period [at 5 min before (ip) or at 5 or 30 min of ligation time (as a bath to PTO)] or (b) reperfusion, post-PTO period [at 1 or 15 min (bath during surgery) or 24 h (ip) reperfusion-time]. We provided gross, microscopy, malondialdehyde, serum enzymes, electrocardiogram, portal, caval, and aortal pressure, thrombosis and venography assessments.

RESULTS

BPC 157 counteracts electrocardiogram disturbances (increased P wave amplitude, S1Q3T3 QRS pattern and tachycardia). Rapidly presented vascular pathway (portal vein-superior mesenteric vein-inferior mesenteric vein-rectal veins-left ileal vein-inferior caval vein) as the adequate shunting immediately affected disturbed haemodynamics. Portal hypertension and severe aortal hypotension during PTO, as well as portal and caval hypertension and mild aortal hypotension in reperfusion and refractory ascites formation were markedly attenuated (during PTO) or completely abrogated (reperfusion); thrombosis in portal vein tributaries and inferior caval vein or hepatic artery was counteracted during portal triad obstruction PTO. Also, counteraction included the whole vicious injurious circle [i.e., lung pathology (severe capillary congestion), liver (dilated central veins and terminal portal venules), intestine (substantial capillary congestion, submucosal oedema, loss of villous architecture), splenomegaly, right heart (picked P wave values)] regularly perpetuated in ischemia and progressed by reperfusion in Pringle rats.

CONCLUSION

BPC 157 resolves pringle maneuver-damage in rats, both for ischemia and reperfusion.

Glutamine prevents oxidative stress in a model of portal hypertension

AIM

To evaluate the protective effects of glutamine in a model of portal hypertension (PH) induced by partial portal vein ligation (PPVL).

METHODS

Male Wistar rats were housed in a controlled environment and were allowed access to food and water ad libitum. Twenty-four male Wistar rats were divided into four experimental groups: (1) control group (SO) - rats underwent exploratory laparotomy; (2) control + glutamine group (SO + G) - rats were subjected to laparotomy and were treated intraperitoneally with glutamine; (3) portal hypertension group (PPVL) - rats were subjected to PPVL; and (4) PPVL + glutamine group (PPVL + G) - rats were treated intraperitoneally with glutamine for seven days. Local injuries were determined by evaluating intestinal segments for oxidative stress using lipid peroxidation and the activities of glutathione peroxidase (GPx), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) after PPVL.

RESULTS

Lipid peroxidation of the membrane was increased in the animals subjected to PH (P < 0.01). However, the group that received glutamine for seven days after the PPVL procedure showed levels of lipid peroxidation similar to those of the control groups (P > 0.05). The activity of the antioxidant enzyme GTx was decreased in the gut of animals subjected to PH compared with that in the control group of animals not subjected to PH (P < 0.01). However, the group that received glutamine for seven days after the PPVL showed similar GTx activity to both the control groups not subjected to PH (P > 0.05). At least 10 random, non-overlapping images of each histological slide with 200 × magnification (44 pixel = 1 μm) were captured. The sum means of all areas, of each group were calculated. The mean areas of eNOS staining for both of the control groups were similar. The PPVL group showed the largest area of staining for eNOS. The PPVL + G group had the second highest amount of staining, but the mean value was much lower than that of the PPVL group (P < 0.01). For iNOS, the control (SO) and control + G (SO + G) groups showed similar areas of staining. The PPVL group contained the largest area of iNOS staining, followed by the PPVL + G group; however, this area was significantly smaller than that of the group that underwent PH without glutamine (P < 0.01).

CONCLUSION

Treatment with glutamine prevents gut mucosal injury after PH in rats.

Long-term efficacy of subtotal splenectomy due to portal hypertension in cirrhotic patients

Background

Portal hypertension (PHT) requires invasive measures to prevent rupture and bleeding of esophagogastric varices; however, the long-term results of subtotal splenectomy plus fixation of the retrosternal omentum majus (SSFROM) have not been reported. Specifically, the advantages and disadvantages of surgery that preserves the spleen and the long-term hematologic effects have not been described.

Study design

Our studies relating to SSFROM commenced in February 1999. As of April 2014 we have performed 256 subtotal splenectomies The records of 65 patients with PHT who underwent SSFROM were reviewed retrospectively.

Results

Four patients died within 4 years of surgery, with a 4-year survival rate of 94 %; the 11-year survival rate was 60 %. Eleven patients (17 %) had re-bleeding from esophagogastric varices. The white blood cell and platelet counts were higher 6 and 11 years post-operatively compared with pre-operative values (P < 0.01). Portal venous diameter, portal venous flow volume, splenic artery flow volume, as well as splenic length, thickness, and average cross-sectional areas were shown to be significantly constricted or decreased (P < 0.01). The proportion of serum CD3+ T cells, CD4+ T cells, and CD8+ T cells was increased (P < 0.01), while the serum levels of macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor were significantly decreased (P < 0.01). There was no significant change in the serum levels of IgA, IgM, IgG, and Tuftsin (P > 0.05). DSA demonstrated that 15 cases formed collateral circulations between the portal vein and superior vena cava.

Conclusion

SSFROM provide long-term hemostasis for esophagogastric variceal bleeding in PHT and corrected hypersplenism. SSFROM is an effective treatment for patients with PHT in whom long-term survival is expected.

Unfeasible experimental model of normothermic hepatic ischemia and reperfusion in rats using the Pringle maneuver

BACKGROUND

The negative result of a research does not always indicate failure, and when the data do not permit a proper conclusion, or are contrary to the initial project, should not simply be discarded and archived.

AIM

To report failure after performing experimental model of liver ischemia and reperfusion normothermic, continuous or intermittent, in small animals aiming at the study of biochemical and histological parameters after postoperative recovery.

METHODS

Fifteen Wistar rats were divided into three groups of five animals each; all underwent surgery, the abdomen was sutured after the proposed procedures for each group and the animals were observed for 6 h or until they died, and then were reoperated. In Group 1, control (sham-operated): dissection of the hepatic hilum was performed; in Group 2: clamping of the hepatic hilum for 30 m; in Group 3: clamping of the hepatic hilum for 15 m, reperfusion for 5 m and another 15 m of clamping. Data from Groups 2 and 3 were compared with Student's t test.

RESULTS

All animals of Group 1 survived for 6 h. Two animals in Group 2 died before the 6 h needed to validate the experiment; two did not recover from anesthesia and one survived until the end. In Group 3, four animals died before the 6 h established and one of them survived the required time. Only one animal in Group 2 and one in Group 3 survived and were able to accomplish the study. There was no statistical significance when the results of Groups 2 and 3 were compared (p>0.05).

CONCLUSION

The death of six animals before the necessary period of observation turned the initial proposal of the experiment unfeasible.

Constriction rate variation produced by partial ligation of the portal vein at pre-hepatic portal hypertension induced in rats

BACKGROUND

Partial portal vein ligation causes an increase in portal pressure that remains stable even after the appearance of collateral circulation, with functional adaptation to prolonged decrease in portal blood flow.

AIM

To assess whether different constriction rates produced by partial ligation of the vein interfere with the results of this experimental model in rats.

METHODS

Three groups of five rats each were used; in group 1 (sham-operated), dissection and measurement of portal vein diameters were performed. Portal hypertension was induced by partial portal vein ligation, reducing its size to 0.9 mm in the remaining 10 animals, regardless of the initial diameter of the veins. Five animals with portal hypertension (group 2) underwent reoperation after 15 days and the rats in group 3 after 30 days. The calculation of the constriction rate was performed using a specific mathematical formula (1 - π r 2 / π R2) x 100% and the statistical analysis with the Student t test.

RESULTS

The initial diameter of the animal's portal vein was 2.06 mm, with an average constriction rate of the 55.88%; although the diameter of the veins and the constriction rate in group 2 were lower than in group 3 (2.06 mm - 55,25% and 2.08 mm - 56.51%, respectively), portal hypertension was induced in all rats and no significant macroscopic differences were found between the animals that were reoperated after 15 days and after 30 days respectively, being the shorter period considered enough for the evaluation. Comparing the initial diameter of the vein and the rate of constriction performed in groups 2 and 3, no statistic significance was found (p>0.05).

CONCLUSION

Pre-hepatic portal hypertension in rat can be induced by the reduction of the portal vein diameter to 0.9 mm, regardless the initial diameter of the vein and the vessel constriction rate.

Volume calculation of rats' organs and its application in the validation of the volume relation between the abdominal cavity and the hernial sac in incisional hernias with "loss of abdominal domain"

BACKGROUND

The calculation of the volume ratio between the hernia sac and the abdominal cavity of incisional hernias is based on tomographic sections as well as the mathematical formula of the volume of the ellipsoid, which allows determining whether this is a giant hernia or there is a "loss of domain". As the images used are not exact geometric figures, the study of the volume of two solid organs of Wistar rats was performed to validate these calculations.

AIM

To correlate two methods for determining the volume of the kidney and spleen of rats, comparing a direct method of observation of the volume with the mathematical calculation of this value.

METHODS

The volume of left kidney, geometrically more regular, and spleen, with its peculiar shape, of ten animals was established in cubic centimeters after complete immersion in water with the aid of a beaker graduated in millimeters. These values ​​were compared with those obtained by calculating the same volume with a specific mathematical formula: V = 4/3 × π × (r1 x r2 x r3). Data were compared and statistically analyzed by Student's t test.

RESULTS

Although the average volume obtained was higher through the direct method (1.13 cm3 for the left kidney and 0.71 cm3 for the spleen) than the values ​​calculated with the mathematical formula (0.81 cm3 and 0.54 cm3), there were no statistically significant differences between the values ​​found for the two organs (p>0.05).

CONCLUSION

There was adequate correlation between the direct calculation of the volume of the kidney and spleen with the result of mathematical calculation of these values ​​in the animals' studies.