Abstract: Objective:To investigate the effect of the peritoneal lymphatic stomata on intraabdominal infection and the regulatory mechanism of angiotensin Ⅱ receptor specific inhibitor PD123319 on peritoneal lymphatic stomata.
Methods:The experimental study was adopted. Forty rats were divided into the control group, sham operation group, intraabdominal infection group and intraabdominal infection drug intervention group by the random number table, every group had 10 rats. The classic appendix perforation (CLP) intraabdominal infection model was established in the abdominal infection group. After establishing the model of abdominal infection, PD123319 solution was injected intraperitoneally immediately (0.2 g/kg) in the abdominal infection drug intervention group. Abdominal cavity of the rats in the sham operation group was opened, and then was shut after flipping the intestine. The rats in the control group, sham operation group and intraabdominal infection group were treated with intraperitoneal injection of 1ml strokephysiological saline solution. After 2 hours, the rats were sacrificed, and peritoneal tissue was taken for the following tests. (1) The aperture size and distribution density of peritoneal lymphatic stomata were observed by scanning electron microscope (SEM). (2) The nitric oxide (NO) concentration in the peritoneal tissues was detected using nitric oxide nitric acid reduction method. (3) The expressions of endothelial nitric oxide synthase(eNOS)and PhosphoeNOS (PeNOS) were detected by the Western blot. (4) The intracellular Ca²⁺concentration were detect by flow cytometry. Measurement data with normal distribution were presented as ±s. The comparison among groups was analyzed using the ANOVA and pairwise comparison was analyzed by the LSD test.
Results:(1) The aperture size and distribution density of the peritoneal lymphatic stomata in the control group, sham operation group, intraabdominal infection group and intraabdominal infection drug intervention group were respectively (2.3±0.4)μm, (2.5±0.5)μm, (4.7±0.5)μm, (3.8±0.5)μm and (2.0±0.8)×10⁸/m2, (2.1±0.7)×10⁸/m2, (6.2±1.3)×10⁸/m2, (4.6±1.4)×10⁸/m2, with statistically significant differences among the 4 groups (F=98.130, 56.780, P<0.05). There were statistically significant differences in the aperture size and distribution density of the peritoneal lymphatic stomata between the intraabdominal infection group and control group or intraabdominal infection drug intervention group (t=11.586, 8.573, 3.854, 3.098, P<0.05) and no statistically significant differences between the control group and sham operation group (t=1.281, 0.514, P>0.05). (2) The concentrations of NO in the peritoneal tissues in the control group, sham operation group, intraabdominal infection group and intraabdominal infection drug intervention group were respectively (0.380±0.024)μmol/gprot, (0.450±0.020)μmol/gprot, (1.253±0.033)μmol/gprot and (0.579±0.035)μmol/gprot, with a statistically significant difference among the 4 groups (F=52.725, P<0.05). There were statistically significant differences in the concentration of NO between the intraabdominal infection group and control group or intraabdominal infection drug intervention group (t=10.536, 67.798, P<0.05) and no statistically significant difference in the concentration of NO between the control group and sham operation group (t=2.007, P>0.05). (3) The results of Western blot showed that the expressions of eNOS and PeNOS in the control group, sham operation group, intraabdominal infection group and intraabdominal infection drug intervention group were respectively (0.591±0.028)U/mg, (0.603±0.007)U/mg, (0.615±0.027)U/mg, (0.626±0.026)U/mg and (0.578±0.003)U/mg, (0.603±0.071)U/mg, (0.773±0.033)U/mg, (0.710±0.012)U/mg, with no statistically significant difference in the expression of eNOS among the 4 groups (F=0.902, P>0.05) and with a statistically significant difference in the expression of PeNOS among the 4 groups (F=205.062, P<0.05). There were statistically significant differences in the expression of PeNOS between the control group and sham operation group or intraabdominal infection group (t=7.678, 13.322, P<0.05) and between the intraabdominal infection group and intraabdominal infection drug intervention group (t=4.035, P<0.05). (4) The results of flow cytometry showed that Ca²⁺ concentration in the control group, sham operation group, intraabdominal infection group and intraabdominal infection drug intervention group were respectively 82.200%±0.060%, 81.730%±0.052%, 21.980%±0.010%, 29.500%±0.004%, showing a statistically significant difference between the 4 groups (F=21 271.030, P<0.05). There were statistically significant differences in the Ca²⁺ concentration between the intraabdominal infection group and control group (t=164.750, P<0.05) and between the intraabdominal infection group and intraabdominal infection drug intervention group (t=21.338, P<0.05), and no statistically significant difference between the control group and sham operation group (t=1.861, P>0.05).
Conclusion: The intra-abdominal infection could increase aperture size and distribution density of peritoneal lymphatic stomata, and PD123319 may be through inhibiting the activation of NO synthase to decrease the concentration of NO, enhance the concentration of Ca²⁺ in peritoneal mesothelial cells and reduce the opening of peritoneal lymphatic stomata.