Reduction of primary postoperative adhesion formation under calcium channel blockade in the rabbit

The Therapeutic Potential of Targeting Key Signaling Pathways as a Novel Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Peritoneal adhesions (PA) are a common complication of abdominal operations. A growing body of evidence shows that inhibition of inflammation and fibrosis at sites of peritoneal damaging could prevent the development of intra-abdominal adhesions.

METHODS

A search of PubMed, Medline, CINAHL and Embase databases was performed using the keywords 'postsurgical adhesion', 'post-operative adhesion', 'peritoneal adhesion', 'surgery-induced adhesion' and 'abdominal adhesion'. Studies detailing the use of pharmacological and non-pharmacological agents for peritoneal adhesion prevention were identified, and their bibliographies were thoroughly reviewed to identify further related articles.

RESULTS

Several signaling pathways, such as tumor necrosis factor-alpha, tissue plasminogen activator, and type 1 plasminogen activator inhibitor, macrophages, fibroblasts, and mesothelial cells play a key part in the development of plasminogen activator. Several therapeutic approaches based on anti-PA drug barriers and traditional herbal medicines have been developed to prevent and treat adhesion formation. In recent years, the most promising method to prevent PA is treatment using biomaterial-based barriers.

CONCLUSION

In this review, we provide an overview of the pathophysiology of adhesion formation and various agents targeting different pathways, including chemical agents, herbal agents, physical barriers, and clinical trials concerning this matter.

Ligustrazine nanoparticles nano spray's activation on Nrf2/ARE pathway in oxidative stress injury in rats with postoperative abdominal adhesion

Background

Postoperative abdominal adhesions formation is considered a significant clinical entity implicating the healing process following major pelvic and abdominal surgery, with serious clinical complications and need for substantial health care expenditures. However, setting a physical barrier between the damage site and the neighboring tissues is a convenient and highly valid way to minimize or prevent peritoneal adhesions. The present experimental study evaluated the preventive effect of ligustrazine nanoparticles nano spray (LNNS) on postoperative abdominal adhesion in rats and explored its mechanism.

Methods

Sixty male Sprague Dawley (SD) rats were randomly divided into sham operation group, control group, sodium hyaluronate group and low, medium, and high dose LNNS groups. All groups were prepared with abdominal adhesion models except for the sham operation group. The models were made by opening the abdominal cavity to and filing the serosa in ileocecal junction. The abdominal cavity of rats in the sham operation group were only opened and sutured. The wound surface of rats in the sodium hyaluronate group, low, medium, and high dose LNNS groups were sprayed with sodium hyaluronate gel (0.5 mL/kg) and LNNS (2.5, 5, and 10 mL/kg). Rats in each group were sacrificed 7 days later. Degree of adhesion was evaluated by naked eyes and the pathological sections were scored afterwards. The collagen synthesis in adhesion tissues was detected by Masson's trichrome stain, and the activities of reactive oxygen species (ROS), nitric oxide (NO), superoxide dismutase (SOD) and malondialdehyde (MDA) in peritoneal fluid were detected with the method of chromogenic substrate. Levels of TNF-α and IL-1β in serum, and the protein levels of MCP-1 and MMP-9 in adhesion tissues were detected by ELISA and. immunohistochemistry respectively. RT-PCR and Western blot were utilized to identify the expression levels of Nrf2, heme-oxygenase-1, NQO1 mRNA and protein in adherent intestinal tissues.

Results

Compared with the control group, the incidence of postoperative abdominal adhesions decreased in the low, medium and high dose LNNS groups, while the expression of SOD in the peritoneal fluid significantly increased. The expression levels of ROS, MDA and NO were reduced remarkably (P<0.05), so were the expression levels of serum TNF-α and IL-1β (P<0.01) and the expression of MCP-1 protein in adhesion tissues. The MMP-9 protein expression, and Nrf2, heme-oxygenase-1, NQO1 mRNA and protein expressions increased.

Conclusions

LNNS with medium or high dose can significantly reduce the incidence of postoperative abdominal adhesions, the mechanism of which may be the activation of Nrf2/ARE pathway, resulting in the up-regulation of Nrf2, heme-oxygenase-1, NQO1 and mRNA expression, as well as the levels of TNF-α and IL-1β in peripheral blood and the expression of MCP-1 protein in adhesion tissues. Meanwhile, the content of MMP-9 protein in adhesion tissues were raised, and oxidative stress and inflammatory response are released.

Fucoidan film safely inhibits surgical adhesions in a rat model

BACKGROUND

The purpose of this study was to evaluate the in vivo efficacy of 13 compounds and to further characterize the load limiting and potential toxicity of the most efficacious compound. The cascade of biochemical and molecular events that results in the formation of postsurgical adhesions provides numerous theoretical opportunities for prophylactic intervention.

METHODS

Candidate agents were loaded into sodium hyaluronate (HA) films and administered to male Sprague-Dawley rats using a cecal-sidewall model of surgical adhesions. An adhesion score was obtained for each rat based on the strength and extent of the adhesions. The most efficacious agent, fucoidan, was further evaluated in a load-limiting study with a concentration range of 0.0033 to 33% w/w per film. The potential toxicity of fucoidan was evaluated in a separate study by comparison of hematology findings, blood chemistry, urinalysis, and incision thickness from rats administered control films or 33% w/w fucoidan films 1 to 4 d prior to sacrifice.

RESULTS

Fucoidan loaded films reduced adhesion scores by approximately 90% compared with control films (P<0.05). A total of 50% to 100% of animals were adhesion free at fucoidan film loadings of 0.33% to 33% w/w compared with all control film animals having adhesions. No adverse effects were observed from 33% w/w fucoidan films equivalent to approximately 30 mg fucoidan/kg body weight.

CONCLUSIONS

Local administration of fucoidan film during rat cecal-sidewall surgery safely reduced adhesion scores by approximately 90% and resulted in 50% to 100% of animals being adhesion free.

Prevention of postoperative peritoneal adhesions

Adhesions are bands of tissue that connect organs together. It is frequently reported after surgery and remains a major problem for health and society. Efforts to prevent or reduce peritoneal adhesions mostly have been unsuccessful, hindered by their empirical basis, lack of good predictive animal models and complexity of adhesion pathogenesis. Although a good surgical technique is a crucial part of adhesion prevention, the technique alone cannot effectively eliminate the adhesions. Thus, there remains a room for further research. A comprehensive literature review of published experimental and clinical studies of adhesion prevention was carried out at the University of Bristol electronic library (MetaLib) with cross-search of seven different medical databases (AMED-Allied and Complementary Medicine Database, BIOSIS Previews on Web of Knowledge, Cochrane Library, Embase and Medline on Web of Knowledge, OvidSP and PubMed) by using key words (peritoneal adhesions, postoperative adhesions, prevention) to explore the progress in different surgical strategies and adjuvant materials used to prevent adhesions formation and reformation. By the end of the study, recommendations formulated for surgeons to be followed during the operations to prevent, as much as possible, the postoperative adhesions.

Postsurgical adhesion formation and prevention – recent developments with regard to the consecutive stages in adhesion formation

The formation of adhesions is a significant clinical problem. Complications like bowel obstruction and chronic pelvic pain are known to be related to adhesion formation. Besides these complications, adhesions do play an additional role in the gynaecological patient. Interference with the functioning of the fallopian tubes and ovaries disturbs ovum pickup and sperm transport and may compromise the fertility of patients.

Effect of reactive oxygen species scavengers, antiinflammatory drugs, and calcium-channel blockers on carbon dioxide pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

BACKGROUND

Postoperative adhesions are a clinical problem. They can cause female infertility, intestinal obstruction, chronic pelvic pain, and difficulties at the time of reoperation. A variety of approaches described to prevent adhesions have shown variable and inconsistent results. Therefore, this study aimed to evaluate most known substances in a laparoscopic mouse model to obtain quantitative and comprehensive information on adhesion prevention. Specifically, this first study aimed to investigate the effects of reactive oxygen species (ROS) scavengers, antiinflammatory agents, and a calcium-channel blocker on pneumoperitoneum-enhanced adhesions.

METHODS

Adhesions were induced during laparoscopy in BALB/c female mice by creation of a bipolar lesion. Carbon dioxide (CO2) pneumoperitoneum was maintained for 60 min using humidified CO2. Six experiments were conducted to evaluate the effects of ROS scavengers (superoxide dismutase [SOD], catalase, melatonin, and ascorbic acid), antiinflammatory agents (dexamethasone, tenoxicam, ibuprofen, parecoxib, nimesulide, anti-tumor necrosis factor [TNF]-alpha), and a calcium-channel blocker (diltiazem). Adhesions were scored after 7 days during laparotomy.

RESULTS

Adhesions were reduced by SOD (p < 0.01, proc general linear methods (GLM) of experiments 1 and 2), diltiazem (p = 0.05, Wilcoxon), and dexamethasone (p < 0.03), but not by nonsteroidal antiinflammatory drugs (NSAIDs) nor by anti-TNF-alpha. When all the experiments were grouped for analysis, adhesions also decreased with one and three doses of SOD (p < 0.01 and p < 0.01, respectively) and with one and three doses of ascorbic acid (p < 0.02 and p = 0.05, respectively).

CONCLUSIONS

These experiments confirm that SOD, diltiazem, and dexamethasone can decrease adhesion formation. The absence of effect from the other antiinflammatory drugs and anti-TNF-alpha is surprising.

Prevention of adhesions in gynaecological endoscopy

Adhesions resulting from gynaecological endoscopic procedures are a major clinical, social and economic concern, as they may result in pelvic pain, infertility, bowel obstruction and additional surgery to resolve such adhesion-related complications. Although the minimally invasive endoscopic approach has been shown to be less adhesiogenic than traditional surgery, at least with regard to selected procedures, it does not totally eliminate the problem. Consequently, many attempts have been made to further reduce adhesion formation and reformation following endoscopic procedures, and a wide variety of strategies, including surgical techniques, pharmacological agents and mechanical barriers have been advocated to address this issue. The present review clearly indicates that there is no single modality proven to be unequivocally effective in preventing post-operative adhesion formation either for laparoscopic or for hysteroscopic surgery. Furthermore, the available adhesion-reducing substances are rather expensive. Since excellent surgical technique alone seems insufficient, further research is needed on an adjunctive therapy for the prevention and/or reduction of adhesion formation following gynaecological endoscopic procedures.

Inhibitory effects of verapamil isomers on the proliferation of choroidal endothelial cells

PURPOSE

To evaluate the effects of verapamil isomers on in vitro proliferation of bovine choroidal endothelial cells (CECs).

MATERIALS AND METHODS

CECs were isolated from bovine eyes and cultured in endothelial growth medium (EGM). For the proliferation assays, CECs were exposed to verapamil isomers (0.1-100 microM) in EGM with 2% fetal bovine serum or basic fibroblast growth factor (bFGF) (10 ng/ml). After 72 h of incubation with the desired drug, the cellular proliferation was determined by an MTT assay and a BrdU assay. In addition, the drug toxicity on CECs stimulated with EGM was evaluated by cell counting with trypan blue.

RESULTS

All verapamil isomers inhibited the bFGF- or medium-stimulated growth significantly in a concentration range of 10-40 microM without toxicity. No significant differences were seen between the inhibitory effects of the various isomers. Cell toxicity was detected at a concentration of 100 microM verapamil isomers on EGM-stimulated CECs.

CONCLUSION

The results demonstrate the efficacy of all verapamil isomers in inhibiting CEC proliferation involved in the process of choroidal neovascularization. D: -(+)-Verapamil may be recommended for further in vivo evaluation in an animal model of exudative AMD; it has fewer systemic and local side effects because calcium channels are not blocked.

Prevention of adhesions by bioresorbable tissue barrier following laparoscopic intraabdominal mesh insertion

Intraabdominal adhesions represent a significant problem because of the morbidity associated with adhesive disease, including small bowel obstruction, difficulties in reoperative surgery, and possibly chronic pain. Coating solution of sodium hyaluronate (Sepracoat; Genzyme Production-Surgical Products, Cambridge, MA) was studied in New Zealand white rabbits to determine its potential role for prevention of postoperative adhesions following laparoscopic intraabdominal mesh insertion. A 2-cm polypropylene mesh was inserted laparoscopically to the left iliac fossa and fixed to anterior abdominal wall using a single prolen suture. Group 1 (n = 10) acted as the control group. Mesh was coated using 4% sodium hyaluronate in phosphate buffered saline (Sepracoat) in Group 2 (n = 10). Fourteen days later, all animals underwent diagnostic laparoscopy, and findings were recorded. All animals then were killed, the abdominal cavities were inspected, and adhesions were graded from 0 to 4. All meshes were removed and sent for histologic examination. The degrees of inflammation, fibrosis, and congestion were scored. No adhesions were seen on trocar sites on both groups. Eight of 10 animals in the control group and 5 of 10 animals in the study group had intraabdominal adhesions. The scoring of adhesions revealed that study group had only one (10%) significant adhesion, whereas the control group had eight (80%; < 0.001). Our study suggests that the Sepracoat reduces the incidence and severity of abdominal adhesions following laparoscopic mesh insertion and should be considered as a prophylactic agent, especially in those undergoing laparoscopic transabdominal mesh repair for hernia.

Sodium polyacrylate potentiates the anti-adhesion effect of a cellulose-derived polymer

Available methods for postoperative adhesion prevention are insufficient. A previous study demonstrated that LM-200, a bioadhesive cellulose derivative was effective in reducing adhesions. Increasing the viscosity of a polymer solution enhances the tissue separating properties. Theoretically, a combination of sodium polyacrylate (PA) and LM-200 would give more viscous solutions than LM-200 alone, and thus be more efficacious. Therefore the efficacy of various combinations of LM-200 and PA was investigated. A lesion was created in the peritoneum of mice. The solutions to be tested, or saline, were given intraperitoneally. One week post-operatively, adhesion formation was quantified and expressed as a percentage of the original lesion covered with adhesions. PA (0.01 and 0.03 wt%) given separately did not differ in adhesion reducing effect from LM-200 (p = 0.3710 and 0.3481) but PA (0.1 wt%) resulted in significantly less adhesion formation (p = 0.0004). The effect of LM-200 increased significantly when adding PA (0.01 wt%) (p = 0.0007) or PA (0.03 wt%) (p < 0.0001). When adding PA (0.1 wt%) the effect was even more pronounced (p < 0.0001). The combination of a bioadhesive cellulose derivative and the polymer PA, was effective in reducing postoperative adhesion formation and a dose-dependent increase in efficacy was obtained compared to using the two components separately.

Surgical sterilization in small mammals. Spay and castration

The intrinsic physiologic and anatomic differences between small exotic mammals and the species that are more familiar to veterinary practitioners (i.e., dogs and cats) are substantial. This discussion is limited to rabbits, mice and rats (murid rodents), hamsters and gerbils (cricetid rodents), and guinea pigs and chinchillas (hystricomorph rodents). In addition to their anatomic and physiologic differences, differences in behaviors, such as their reaction to stress and pain, exist. Preoperative and postoperative care, basic surgical techniques unique to these species, and useful materials are discussed.

Association between the expression of mast cell chymase and intraperitoneal adhesion formation in mice

BACKGROUND

Adhesion formation is a major source of postoperative morbidity and mortality. Mast cells and their major protease, chymase, have been shown to participate in the healing process as well as in tissue remodeling. We aimed to identify the role of mast cells in intraperitoneal adhesion formation and to assess whether there is an association between the expression of mast cell chymase and adhesion formation.

MATERIALS AND METHODS

Both mast cell-deficient W/W(V) mice and congenic +/+ mice received a standardized lesion produced by cecal scraping and the application of 95% ethanol. Adhesions were assessed blindly 1 week later using a standardized scale. In addition, histamine content, mast cell numbers, and chymase activity in cecum as well as at the healing sites were evaluated before and 7 days after surgical injury.

RESULTS

A significant reduction in adhesion formation was seen in mast cell-deficient W/W(V) mice (P < 0.05). In the normal cecum, histamine content did not significantly differ between W/W(V) and +/+ mice. Chymase activity in cecum was detected in control +/+ mice, but not in W/W(V) mice. Mast cell numbers and chymase activity levels at the healing sites of +/+ mice were significantly increased 7 days after surgery.

CONCLUSIONS

Our results indicate that mast cells contribute to intraperitoneal adhesion formation in mice, and suggest that chymase originating from mast cells is important in the development of adhesions.

Effects of antiadhesive agents on the healing of intestinal anastomosis

PURPOSE

The effects of antiadhesive agents on the healing of intestinal anastomosis were investigated.

METHODS

Eighty rats were divided into eight groups. Colotomy and anastomosis were performed to all rats. Saline solution (control), carboxymethylcellulose, aprotinin, verapamil, tenoxicam, cyclosporine, and dextran 70 were administered intraperitoneally. Vitamin E was administered intramuscularly. The rats were killed 15 days later. Anastomotic healing was assessed by bursting pressure and the hydroxyproline content of the anastomotic tissues. The results were evaluated by Mann-Whitney U test.

RESULTS

The mean (+/- standard deviation) bursting pressures of carboxymethylcellulose, cyclosporine, and aprotinin groups (108 +/- 6.73, 122.5 +/-14.39, and 127 +/- 20.23, respectively) were significantly lower than those of the control group (234 +/- 6.19). The mean level of hydroxyproline in the anastomotic tissues was significantly lower in the carboxymethylcellulose and cyclosporine groups (8.92 +/- 0.6 and 8.32 +/- 0.63) than that in the control group (16.33 +/- 0.68).

CONCLUSION

These findings indicate that carboxymethylcellulose and cyclosporine had adverse effects on intestinal anastomosis in rats.

An in vivo evaluation of a chondroitin sulfate solution to prevent postoperative intraperitoneal adhesion formation

PURPOSE

The goal of this study was to determine the efficacy of a single intraperitoneal administration of a chondroitin sulfate solution in preventing postoperative adhesion formation. METHODS. Twenty-five Sprague-Dawley rats had a 1-cm(2) area of cecal serosa abraded. Controls (CON, n = 5) received no treatment, the chondroitin sulfate group (CS, n = 10) received chondroitin sulfate (0.013 g/kg) in 0.9% NaCl intraperitoneally (ip), and vehicle controls (VC, n = 10) received an equal volume of 0.9% NaCl solution ip before the abdomen was closed. All animals were sacrificed on postoperative day 10. The extent of adhesion was quantified according to Mazuji's adhesion grade (0 to 4: 0 = no adhesion and 4 = very dense adhesion) and quantitated after H&E, trichome, and immunohistochemical staining for fibrin and collagen type I and type III using digital image analysis.

RESULTS

The mean Mazuji's adhesion grade in the CON was 4.0 +/- 0.0, in the VC 2.60 +/- 0.37, and in the CS 1.3 +/- 0.42 (P < 0.01 for CS vs CON and P < 0.05 for CS vs VC comparisons). The mean gray-scale intensity (0-255: 0 = dense amount and 255 = none) of adhesion density in the CON was 105. 5 +/- 5.5, in the VC 125 +/- 15.0, and in the CS 178.3 +/- 21.0 (P < 0.01 for CS vs CON and P < 0.05 for CS vs VC comparisons). The mean adjusted intensity stain indices (AISI) for fibrin and collagen type I in the CON were 59 +/- 17 and 53 +/- 19, in the VC 27 +/- 3 and 25 +/- 7, and in the CS 16 +/- 5 and 6 +/- 3, respectively (P < 0.05 between CS and CON comparisons). The AISI of collagen type III was not significant among all the groups (P > 0.1).

CONCLUSIONS

The extent of early postoperative intra-abdominal adhesion formation as determined by gross assessment and from quantitation of fibrin and collagen type I deposition was significantly reduced by a single intraperitoneal administration of a chondroitin sulfate solution.

The pharmacokinetics and effects of diltiazem in rabbits

PURPOSE

To investigate the effect of diltiazem on wound healing after the creation of conjunctival flaps in rabbit eyes. Also, to investigate the pharmacokinetics of diltiazem in rabbits after subconjunctival and topical administration.

METHODS

For the histopathological study, a limbal-based flap was prepared and diltiazem was injected subconjunctivally for five days after the surgery. The rabbits were euthanised 20 days after surgery. The effectiveness of diltiazem on wound healing was evaluated by histopathological examination and measurement of the thickness of subconjunctival fibrous tissue. For the pharmacokinetic study, diltiazem was applied topically or injected subconjunctivally. Aqueous paracenteses were performed 0.5, 1, 2, 4 hours thereafter.

RESULTS

The histopathological study found no difference in thickness of the subconjunctival fibrous tissue in control and diltiazem-treated eyes. No significant toxicity was observed in eyes treated with diltiazem. The peak aqueous concentration was 3.8 +/- 0.4 microg/ml after topical application and 15.3 +/- 1.1 microg/ml after subconjunctival injection. The peak aqueous concentration was achieved 1/2 hours after administration in both cases.

CONCLUSIONS

Diltiazem did not appear to affect wound healing at the dose tested. Topical and subconjunctival diltiazem successfully penetrated the aqueous humor of rabbit eyes.

Verapamil inhibits proliferation, migration and protein kinase C activity in human retinal pigment epithelial cells

The effects of three calcium channel blockers, verapamil, diltiazem and nifedipine, were examined on in vitro proliferation and migration of human retinal pigment epithelial cells. Human retinal pigment epithelial cells were seeded in Dulbecco's modified essential medium with 10% fetal bovine serum and different concentrations of the three calcium channel blockers. After 3 days of treatment, cell proliferation was determined by cell counting and by [3H]-thymidine uptake. Cell viability was determined with trypan blue exclusion. For determination of cell migration, retinal pigment epithelial cells were grown to confluence and then growth-inhibited with mitomycin C. After a 3 mm zone was denuded, the cells were treated with different concentrations of the calcium channel antagonists. After 24 hr, the cells that had migrated over the wound edge were counted. To determine the involvement of protein kinase C in the verapamil effect, its activity was measured in both verapamil-treated and untreated cells. Verapamil dose dependently inhibited serum-induced proliferation of retinal pigment epithelial cells, when measured by cell number (IC50 14.6 microM) or [3H]-thymidine incorporation (IC50 11.3 microM). At concentrations of 15 microM and below, there was no effect on cell viability, as determined by morphology and trypan blue exclusion. Diltiazem inhibited cell proliferation at a concentration of 100 microM; however, 100 microM nifedipine had no effect. Verapamil showed a significant inhibition of serum-induced migration in the range of 10 microM to 0.1 microM. The IC50 of the inhibition of retinal pigment epithelial cell proliferation and migration by verapamil is significantly higher than that seen for effects on calcium channel blockage. Eight micromolar verapamil reversibly inhibited total protein kinase-C activity in retinal pigment epithelial cells suggesting the possibility that the drug may act by inhibiting the protein kinase-C pathway. These data suggest the potential of the calcium channel blocker verapamil as a pharmacological modulator of disorders such as proliferative vitreoretinopathy in which there is increased retinal pigment epithelial cell proliferation and migration.

A pilot study of cyclosporine for the prevention of postsurgical adhesion formation in rats

OBJECTIVE

Our purpose was to evaluate the efficacy of cyclosporine in preventing primary postsurgical adhesions in the rat model.

STUDY DESIGN

Thirty-two Sprague-Dawley rats underwent unilateral uterine horn injury with a combination of unipolar and bipolar cautery. Sixteen of the rats were randomized to the treatment group and received preoperative and daily cyclosporine dosing (10 mg/kg) by gavage for 14 days. At the end of the study all animals were killed, and a standard adhesion scoring system was applied by a blinded examiner.

RESULTS

Adhesions were present in 75% of rats in both groups. Treatment did not affect the total adhesion score.

CONCLUSION

Cyclosporine does not appear promising as a means to decrease postsurgical adhesion formation.

Prevention of adhesions

A survey is given on the literature of the prevention of adhesions. Various methods of adhesion prevention are discussed: limitation of peritoneal injury, inhibition of the inflammatory response, prevention of coagulation of fibrinogen, removal of fibrin and mechanical separation of injured mesothelial surfaces.

Failure of calcium channel blockade to prevent intra-abdominal adhesions in ponies

Intra-abdominal adhesions were created by localized serosal trauma in 11 adult ponies at three locations on the small intestine. Six ponies received verapamil hydrochloride (0.2 mg/kg) subcutaneously every eight hours for three days, and five ponies received an equal volume of saline solution at the same intervals. The investigators were not informed which treatments the ponies received. Systolic, diastolic, and mean carotid arterial pressures and heart rates were measured six hours before surgery, and then 0.5, 1, 1.5, and 8 hours after the first treatment on each day for three days. One pony was euthanatized on day 13 because of colic, and the other 10 ponies were euthanatized 14 days after surgery. Scoring methods were used to assess the severity of adhesion formation and to grade the histologic appearance of the abraded sites. No significant differences were found for rectal temperature, packed cell volume, total plasma proteins, heart rate, and systolic, diastolic, or mean arterial pressures between control and verapamil-treated ponies. No significant differences were detected between the treatment groups for adhesion scores per abraded site, total adhesion scores per pony, the total number of adhesions per pony, or in the histologic scores.

Role of mast cells in peritoneal adhesion formation

Postoperative adhesions are a major cause of bowel obstruction and infertility. Since mast cells in the intestinal wall have been shown to degranulate after bowel manipulation, we investigated a possible role for these cells in peritoneal adhesion formation. Adhesions were created in weanling rats using cecal scraping and the application of 95% ethanol. The rats were treated with saline or one of two mast cell stabilizers, disodium cromoglycate (DSCG) or nedocromil sodium (NED), intraperitoneally 30 minutes before laparotomy and at the time of abdominal closure. The adhesions were assessed blindly 1 week later using a standardized scale. When the results in rats treated with DSCG were compared with those in rats treated with saline, the DSCG rats had significant attenuation of adhesion formation at 2 mg/kg (1.05 +/- 1.0 versus 2.15 +/- 0.8) and 10 mg/kg (1.2 +/- 0.9 versus 2.71 +/- 0.5). The application of NED decreased adhesions at a dose of 100 mg/kg (1.33 +/- 1.2 versus 2.4 +/- 0.8) but not at 10 mg/kg (2.4 +/- 0.8 versus 2.4 +/- 0.8). Histologic analysis using toluidine blue staining was done to assess the effect of DSCG on mast cell degranulation in the same adhesion model. DSCG significantly decreased the number of degranulated mast cells in the bowel wall when compared with saline (7.16 +/- 0.6 mast cells/high-power field [hpf] versus 12.4 +/- 1.9 mast cells/hpf). These data suggest that mast cells play an important role in the initial stages of peritoneal adhesion formation. In the future, pharmacologic inhibition of mast cell degranulation may be a useful adjunct for the prevention of postoperative adhesions.