Page 47 - World Journal of Laparoscopic Surgery

WU Gang et al

MATERIALS AND METHODS immediately after IP anesthesia in the control group. The
plasma β-endorphin concentration increased after the
Animal Grouping
establishment of the CO pneumoperitoneum gradually,
2
SPF-grade SD male rats weighing 190-220 gm (Shanghai and rose to the peak at 10 minutes after continuum of the
Laboratory Animal Center, Chinese Academy of Sciences) CO pneumoperitoneum, and then decreased at 20n and
2
were given free access to tap water and pelleted food 40 minutes gradually. The serum β-EP concentration in
throughout the course of study. Laboratory temperature
group A was 2.74 ± 0.67 ng/ml, 1.57 ± 0.64 ng/ml and
was maintained at 23ºC and relative humidity at 48%.
1.64 ± 0.74 ng/ml at 10, 20 and 40 minutes respectively,
Grouping: 120 rats were equally randomized to four
vs 0.61 ng/ml, 0.65 ng/ml and 0.64 ng/ml in the control
groups before intraperitoneal anesthesia with 1% sodium group (P < 0.01).
thiopental (0.5 ml/100 gm). In group A, CO pneumo-
2
peritoneum was established by abdominal paracentesis at a
Incising the Abdomen Increases Plasma ββ ββ β-EP
stable pressure of 1.0 kPa using a pneumoperitoneum
machine (STORZ 26020S); in group B, a 5 cm abdominal The serum β-EP concentration increased gradually after
incision was made on the upper abdomen of rats without the 5 cm incision was made on the abdomen, rose to the
any disturbance on the incision and abdominal organs; in peak at 10 minutes, and then decreased at 20 and 40 minutes
group C, a 5 cm abdominal incision was made on the upper gradually. The serum β-EP concentration of group A was
abdomen of rats with pulling the intestine with a retractor 2.87 ± 0.47 ng/ml, 1.58 ± 0.61 ng/ml and 1.41 ± 0.79
using 5N pulling power; and in group D, only intraperitoneal ng/ml at 10, 20 and 40 minutes, respectively, which was
anesthesia was performed without any surgical procedure. significantly higher than that of the control group (P < 0.01).
Serum β-EP was measured at 10, 20 and 40 min
postoperatively in every other 10 rats of each group. Serum Enteric Disturbance Accentuates the
β-EP was measured in another 10 rats immediately after Severity of Stress Response
i.p. anesthesia as normal level.
In group A, B and C, serum β-EP was significantly increased
Estimation of Serum ββ ββ β-EP Levels at 10, 20 and 40 minutes compared with the control (P <
0.01). There was no significant difference in plasma β-EP
Reagents and equipment included a plasma β-EP Kit
at 10, 20 and 40 minutes between group A and B, but the
(Department of Neurobiology of the Second Military Medical
University, Shanghai, China), a pneumoperitoneum machine
(STORZ 26020S), a refrigerated centrifuge (DL-8R,
Centrifugal Machinery Research Institute, Shanghai), and
RIA measuring instrument (SN-695, Shanghai).
2 ml blood samples drawn by cardiac puncture were
collected in heparinized Vacutainer tubes containing pre-
cooled 0.3 mol/LEDTA-2Na (20 mg/l) and aprotinin (500
U/ml), and centrifuged immediately at 3000 gm for 15
minutes. The plasma was stored at 75°C for estimation of
the serum β-EP concentration by using a commercial
radioimmunoassay kit.

Statistical Analysis
Significant interactions were decomposed by using simple
main effects F tests. The significance was evaluated at a
level of 0.05. All statistical analyses were performed with
the SPSS statistical software package, version 10.1, by a
personal computer.
Fig. 1: Serum β-EP was significantly increased at 10, 20 and 40
minutes in group A, B and C as compared with that of the control
RESULTS (P < 0.01). There was significant difference in plasma β-EP at 10, 20
and 40 minutes between group B and C (P < 0.01), and also between
CO Pneumoperitoneum Increases Serum β-EP. The mean
2 Group A and C (P < 0.01), but there was no significant difference
serum β-EP concentration was 0.61 ± 0.35 ng/ml between group A and B (P > 0.05)
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