Microvascular repair following a modified crush-avulsion injury in a rat model: effect of recombinant human tissue-type plasminogen activator on the patency rate

The failure rate of replantations following a crush-avulsion type injury is high. This study has been designed to reproduce an effective standardized crush-avulsion injury model to the femoral artery of the rat and evaluate the antithrombotic efficacy of systemic intravenous administration of recombinant human tissue-type plasminogen activator (rt-PA). The crush-avulsion injury was reproduced by using a bulldog clamp and two hemostats and followed by microvascular repair. The animals were divided into three groups of 20 rats each and received either normal saline, heparin 100 U/kg body weight, or rt-PA 3.5 mg/kg body weight intravenously. Patency tests were performed 20 min and 48 h after blood flow reestablishment. Results showed that this experimental crush-avulsion injury model ensures low patency in the control group, whereas systemic rt-PA administration improves the patency rate statistically significantly compared to control and heparin groups at both 20 min and 48 h postrevascularization.     

Microvascular repair following crush-avulsion type injury with vein grafts: effect of direct inhibitors of thrombin on patency rate

The aim of this study was to develop a standardized effective thrombogenic arterial anastomosis model, as usually encountered in clinical practice, and to offer a detailed evaluation of the antithrombotic effect of thrombin's direct inhibitors, antithrombin III and hirudin, as locally applied. Wistar rats were divided into four groups of 12 animals each. The carotid artery sustained a standardized crush-avulsion-type injury (groups B-D). A segment of the afflicted area was removed and replaced by a microvenous graft. Group A had no crush-avulsion injury inflicted; a microvenous graft replaced a simple resection from the center of the carotid artery. During microvascular anastomoses, normal saline (groups A and B), recombinant hirudin (group C), or antithrombin III (group D) were locally applied. Bleeding times were recorded, and patency tests were performed 20 min, 48 h, and 1 week after blood flow reestablishment. All grafts were harvested and examined histologically. Patency tests, 1 week postrevascularization, demonstrated that this experimental crush-avulsion injury model ensured low patency in group B (25%), whereas group A, which had no injury inflicted, achieved a 100% patency rate. The local application of hirudin and antithrombin III significantly increased bleeding times as well as the patency rate (92% and 75%, respectively) compared to group B. These findings indicate the efficiency of the experimental model and the potential use of thrombin's direct inhibitors in microvascular surgery.     

Comparison of single-dose antithrombotic agents in the prevention of microvascular thrombosis.

A model of thrombosis was used to evaluate the efficacy of single-dose heparin, hemodilution, and 40,000 milliwatts dextran in the prevention of microvascular thrombosis. Forty Lewis rats (275 gm body weight) were divided into four groups (n = 10): hemodilution (6 ml NS), single-dose heparin (1 mu/gm), 40,000 mw dextran (0.3 gm/100 gm), and control (0.275 ml NS). After exposure of the superficial femoral arteries, a model of arterial crush with arteriotomy followed by an intimal abrasion was used. The animals randomly received one of the four solutions above. Experimental results included patency rates of 90% at 20 minutes and 10% at 24 hours in the hemodilution group, 100% at 20 minutes, and 70% at 24 hours in the single-dose heparin group, and 100% at both 20 minutes and 24 hours in the dextran group. A 100% thrombosis rate was observed in the control group at 20 minutes and 24 hours. Single-dose heparin and dextran significantly improved patency in comparison to both the control and hemodilution groups at 24 hours (p less than 0.01). Scanning electron microscopy of the vessels revealed thrombus deposition consistent with these findings. These results indicate that single-dose heparin and single-dose dextran reduce thrombosis in this model of microvascular injury.     

Modified crush-avulsion anastomosis model on the rat femoral vein

A crush-avulsion anastomosis model was established on the rat femoral vein. Saline or heparin was used as a luminal topical agent and was allowed to contact the damaged endothelium for 10 min. Patency and coagulation parameters were investigated for 1 week. The heparin treated group had a patency rate of 93% at 1 hr vs. 13% for the saline treated group (P<0.001). At 7 days, the heparin treated group had an 87% patency vs. 7% for the saline-treated group (P<0.001). Scanning electron micrography (SEM) provided evidence of the deposition of the components of early thrombosis in the crushed venous wall. In contrast, the SEM of the heparin treated group shows a paucity of any evidence of thrombus. These results indicate that the rat vein crush-avulsion model is a reliable and reproducible thrombosis model with low patency. The methods used with the topical agent may improve the patency rate in crush avulsion injuries. © 1995 Wiley-Liss, Inc.     

Microvascular repair with 1-mm polytetrafluoroethylene (PTFE) grafts: effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process

The present study assesses the effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process of microvascular polytetrafluoroethylene (PTFE) grafts. Wistar rats were used, divided into four groups of 25 animals each. After dissection of the carotid artery a segment of the vessel, 1 cm long, was resected and replaced by equal length graft. Two different type fibril length (30- or 60-microm) grafts of the same wall thickness (0.18 mm) were used. Normal saline or 3 mg/kg of body weight of rt-PA was applied locally in each group of different fibril length grafts. Patency tests were performed at 15 min and 4 weeks after blood flow was reestablished. All grafts were harvested and examined histologically. The results showed that local application of rt-PA improves patency statistically significantly in both types of fibril length grafts. Patency in 60-microm fibril length grafts was statistically significantly higher than that of 30-microm fibril length grafts, whether rt-PA was used or not. The use of rt-PA had no influence on the healing process of either type of graft.     

A comparison of heparinised saline irrigation solutions in a model of microvascular thrombosis.

The use of heparinised irrigation solutions has become common in microvascular surgery, but the concentration of heparin has been determined empirically. A laboratory model of microvascular thrombosis, employing a crush injury, intimal abrasion, and stasis to the rat superficial femoral artery was used to compare heparinised saline irrigation solutions of various concentrations. The solutions included normal saline (Group I, controls) and heparinised normal saline in concentrations of 10 U/ml (Group III), 250 U/ml (Group IV), and 500 U/ml (Group V). Group I animals had a patency rate of 25% at 20 min and 0% at 24 h. Group II showed a patency rate of 75% at 20 min but fell to 37.5% at 24 h. Patency in Group III was 87.5% at 20 min and at 24 h. Group IV had a 100% patency rate at 20 min and at 24 h. Group V animals were 100% patent at 20 min and 87.5% patent at 24 h. The activated partial thromboplastin time was prolonged in animals exposed to 250 U/ml and 500 U/ml of heparinised saline. Patency was significantly improved in animals exposed to 100 U/ml, 250 U/ml and 500 U/ml when compared to the control group (p less than 0.001). These results suggest that topical heparinised saline administration is of benefit in the prevention of microvascular thrombosis. Higher concentrations tested in this study resulted in a significant increase in patency, but also prolonged the activated partial thromboplastin time. 100 U/ml is the ideal concentration of heparinised saline irrigation because it significantly improved patency but did not produce detectable systemic effects in this model.     

Effects of enoxaparin,standard heparin,and streptokinase on the patency of anastomoses in severely crushed arteries

The effects of topical irrigation with three antithrombotic agents on the patency of anastomosed arteries following crush injury were examined. Following an impact crush injury with a 25 kg crush load, the femoral arteries of rats were divided and then anastomosed. During anastomoses, the vessel lumina were topically irrigated with saline, streptokinase, standard heparin, or enoxaparin (a low molecular weight heparin). The results were evaluated by patency test and histology up to day 56. The thrombosis rate at days 1 and 7 was statistically lower (P<0.05) in the standard heparin and the enoxaparin groups than in the other two groups. The difference between the standard heparin and the enoxaparin groups was not statistically significant. Histology at day 1 showed that thrombus in the occluded vessels adhered to the exposed adventitia in the crushed area or the adventitia was covered by fibrin, red blood cells, and platelet mesh in the patent vessels. The results showed that 1) topical irrigation with standard heparin or enoxaparin solution significantly reduced the thrombosis rate at the anastomosis site of the crushed arteries; and 2) enoxaparin was as effective an antithrombotic agent as standard heparin when topically applied during microvascular anastomoses. © 1995 Wiley-Liss, Inc.     

Antithrombotic efficacy of direct oral anticoagulants on patency rate following microsurgical anastomosis in crushed rat arteries

BackgroundDuring the last decade direct oral anticoagulants (DOAC) have been established in various fields of medicine.Their use in microsurgery has not been evaluated yet though. This study aims to evaluate their efficacy in microsurgery and additionally compare them with a well established antithrombotic agent.Materials and methodsThe right femoral artery of 101 rats divided into 4 groups, was crushed and anastomosed. Group A (20 rats) received placebo therapy (1 ml NaCl 0.9%, orally), while Group B (27 rats), Group C (27 rats) and Group D (27 rats) received rivaroxaban (3 mg/kg, orally), dabigatran (30 mg/kg, orally) and enoxaparin (30 mg/kg, subcutaneously) respectively. All drugs were administered 3 h preoperatively and once daily for the following postoperative days until the sacrifice of the animals. Patency was evaluated at 1st, 7th and 20th postoperative day. Following patency evaluation the rats were sacrificed and the vessels were harvested for histological examination.ResultsNone of the rats died postoperatively. Patency rates of rivaroxaban group (78%), dabigatran group (70%) and enoxaparin group (63%) were statistically similar, but significantly higher than the placebo-treated control group (p < 0.05). Cells with morphologic features of endothelial cells were evident 7 days after the injury.ConclusionThe results of this study demonstrate the following: (1) rivaroxaban and dabigatran through inhibition of thrombus formation significantly enhanced the patency rate compared to placebo treatment (2) the antithrombotic efficacy of rivaroxaban and dabigatran in compromised microvessels was similar to that of enoxaparin, the most widely used antithrombotic agent.     

Do anticoagulation with heparin and protamine reversal alter thrombogenicity of coated and noncoated pulmonary artery catheters?

OBJECTIVE: To clarify the role of anticoagulation with heparin and protamine reversal on the effectiveness of heparin bonding or coating of pulmonary artery catheters in preventing thrombus formation in the Rhesus monkey. DESIGN: A controlled, unblinded, open-labeled study. SETTING: A research laboratory at Tulane School of Medicine (New Orleans, LA). PARTICIPANTS: Twenty-four anesthetized Rhesus monkeys. INTERVENTIONS: The monkeys were assigned to one of four groups. In the first group (group A), non-heparin-coated catheters were inserted into a femoral vein through an incision, advanced proximally for a distance of 30 cm, and left in place for 1 hour. In the second group (group B), heparin-coated catheters were placed and evaluated in the same manner as in group A. In the third group (group C), the primates received 3 mg/kg of heparin intravenously (i.v.) before insertion of a non-heparin-coated pulmonary artery catheter. After the catheter had been in place for 1 hour, protamine, 3 mg/kg i.v., was administered, and the catheter was left in place for an additional hour. In the final group (group D), the primates received 3 mg/kg of heparin i.v. before insertion of a heparin-coated pulmonary artery catheter. After the catheter had been in place for 1 hour, protamine, 3 mg/kg i.v., was administered, and the catheter was left in place for an additional hour. In each group, the catheter was withdrawn with the balloon inflated to minimize any stripping of thrombus from the surface of the catheter. Thrombus was removed from the catheter through a femoral vein cutdown and weighed. Laboratory values were determined for each animal, and clot formation was evaluated in each group. After completion of the study, the animals were returned to the primate breeding colony. MEASUREMENTS AND MAIN RESULTS: There were no significant differences in hematocrit, prothrombin time, partial thromboplastin time, or platelet levels among the four groups; therefore, the data were pooled. Clots were observed on five of six catheters in both groups A and C; however, clot formation was seen in one of six catheters in group B and three of six catheters in group D. There was a statistically significant difference (p < 0.01) in mean clot weight in group A (265 +/- 68 mg; range, 0 to 447 mg) compared with 13 +/- 13 mg in group B (range, 0 to 80 mg). There was no significant difference in mean clot weight in group C (104 +/- 35 mg; range, 0 to 202 mg) compared with group D (24 +/- 16 mg, range, 0 to 98 mg). Additionally, in group C, the mean clot weight was significantly less than in group A. CONCLUSION: Anticoagulation of primates with heparin before catheter insertion imparts some protection to non-coated catheters, and protamine reversal of anticoagulation with heparin may partially negate the protective effect seen with heparin-coated pulmonary artery catheters.     

Microvascular repair following local crush and avulsion vascular injury

A model has been developed demonstrating intimal damage resulting from a combined crush and avulsion injury to the femoral artery of the rat. Revascularization after traumatization is accomplished with microvascular anastomosis of the severed ends. Vascular patency rates at 2 and 7 days postoperatively are low (0-25%) in comparison with control groups (90-100%). A high correlation is found between patency tests performed at 20 minutes and at 2 days after blood flow re-establishment. Systemically administered heparin improves traumatized-vessel patency dramatically.     

Heparin treatment reduces glomerular injury in rats with adriamycin-induced nephropathy but does not modify tubulointerstitial damage or the renal production of transforming growth factor-beta

In this study we investigated the effect of heparin on renal injury and renal transforming growth factor-beta (TGF-beta) production in adriamycin (AD)-injected rats. Thirty-nine female Wistar rats were injected with AD (3.5 mg/kg body weight, i.v.) and 27 with 0.15 M NaCl solution (group C). Fifteen days later we started to inject heparin, 500 U/day, s.c., in 20 of the AD-injected animals (AD-H group). Three months after beginning treatment, urine samples were collected to quantify albumin, creatinine and TGF-beta. The rats were killed and the kidneys removed for histological, immunohistochemical, ELISA and RNA studies. All AD-injected animals showed structural renal changes (p < 0.05). However, the glomerular alterations were less intense in rats from group AD-H (p < 0.05). The percentage of glomerulosclerosis was 0.11 +/- 0.08 in group C, 14.7 +/- 12.8 in group AD (treated only with AD) and 3.42 +/- 2.3 in group AD-H. Renal cortex immunostaining for TGF-beta and mRNA content of this polypeptide was higher in both groups of animals injected with AD compared to controls (p < 0.05). These animals also presented a higher rate of urinary TGF-beta excretion (p < 0.05), which was 202 +/- 11 in group C, 1,103 +/- 580 in group AD and 1,564 +/- 328 pg/mg Ucreat in group AD-H. However, TGF-beta activity in the glomerular-conditioned media from the rats of group AD was higher than in the glomerular-conditioned media from the rats of group AD-H. In conclusion, treatment with heparin reduces glomerular damage in rats with AD-induced nephropathy but does not modify tubulointerstitial lesions or the renal production of TGF-beta.     

Experimental Thromboprophylaxis with Low Molecular Weight Heparin After Microsurgical Revascularization

There is great variability among microsurgeons as regards the use of prophylactic anticoagulant after revascularization and this is probably due to lack of comparative data. Also, there has been much debate regarding the benefit of anti-thrombotic therapies versus the risk of complications such as systemic bleeding and hematoma formation. To evaluate the effectiveness of postoperative low molecular weight heparin (LMWH) as a prophylactic anticoagulant therapy after microsurgical repair of the femoral artery and vein in rats. Randomized, blinded study. The femoral artery and vein of 40 Sprague Dawley rats were sectioned and repaired with microsurgical sutures under general anesthesia. They were randomly divided into 2 groups: Group (A) in which the 20 rats were injected with Enoxaparin subcutaneously at a dose 1.5 mg/kg once daily for 3 successive days; Group (B), the control group, in which 20 rats were injected with isotonic sodium chloride 0.9 % subcutaneously in a blinded fashion. After 7 days, the femoral vessels were re-explored and patency of the femoral vessels was assessed with empty-and-refill test. There were a total of 12 vascular thrombosis among 74 microsurgical repair in both groups with percentage of 16.22 % including, 5 arterial anastomosis and 7 venous anastomosis. The incidence of thrombosis in the treatment group (A) was 18.4 % while the incidence of thrombosis in the control group (B) was 13.8 %. This difference was not statistically significant using Fisher exact test. Postoperative administration of LMWH did not provide the desired protection against thrombosis after microsurgical vascular repair.     

A comparison of irrigation solutions for microanastomoses

A comparative study of irrigating solutions that contained various clot-active substances and/or vasodilating substances was done using a crush injury model of the rat's femoral artery. A routine microanastomosis was done with one of seven irrigation solutions employed in the study. The patency rate of lactated Ringer's solution (10%) (the control solution) was compared with solutions of heparin (35%) urokinase (50%), phentolamine (35%) tissue plasminogen activator (tPA) (15%), a combination of urokinase, heparin, and phentolamine (55%), and a combination of tPA, heparin, and phentolamine (42.5%). Statistically significant improvement in patency rates were obtained with heparin (p less than 0.0005), phentolamine (p less than 0.03), urokinase (p less than 0.001), the tPA, heparin and phentolamine combination (p less than 0.001), and the urokinase, heparin, and phentolamine combination (p less than 0.0001). There seems to be a benefit with the addition of either vasoactive agents or clot-active agents to the microvascular irrigating solution during construction of a compromised microanastomosis.     

体重对成年女性骨矿含量及其标化的影响研究

目的分析不同体重组人群[小体重组(<45 kg)、标准体重组(45~60 kg)、大体重组(>60 kg)]的骨矿含量结果,探索体重对骨矿含量及其标化的影响。方法纳入290例50~80岁绝经后女性,按体重大小分为大体重组、标准体重组、小体重组。通对不同体重组人群的腰椎L_1~4、股骨的骨矿含量及骨密度进行测量,并对测量结果进行比较分析。同时将年龄、体重作为应变量,腰椎或股骨颈骨矿含量作为自变量,进行多重线性回归分析。结果低体重组的腰椎或股骨颈骨密度T值、骨矿含量均明显低于标准体重组和高体重组人群。随着年龄增长,L_1~4及股骨颈骨矿含量均下降,年龄每升高1岁,L_1~4骨矿含量下降0.364 g、股骨颈骨矿含量下降0.031 g;随着体重增长,L_1~4及股骨颈骨矿含量均升高,体重每增长1 kg,L_1~4骨矿含量升高0.548 g、股骨颈骨矿含量升高0.025 g。结论成年女性的体重与骨矿含量显著正相关,因此,体重是骨矿含量标化的重要指标之一,可以避免骨质疏松的漏误诊。     

The effect of nifedipine on the patency of microvascular anastomosis in rats

Despite advances in microsurgical technique and experience in clinical microvascular surgery, there remains the possibility of vessel thrombosis. Factors that may contribute to vascular pedicle thrombosis include operative trauma, pedicle malposition, kinking, hypercoagulability and arterial vasoconstriction. The purpose of this study was to evaluate the effect of intravenous administration of nifedipine on the patency of the microvascular anastomosis of the femoral artery in rats. A total of 60 rats were used and divided into three groups. The first group (A) was used as a control group with no medical agent, the second group (B) was medicated with heparin, and the third group (C) was medicated with nifedipine. Patency was assessed with the distal empty refill test, one hour (1) and forty-eight hours (48) after completion of the anastomosis. The nifedipine and heparin treated groups (B & C) did not show higher patency rate compared to the control group (A). There was no statistically significant difference of patency percent after 1 hour and 48 hours among the three groups (p = 0.231/p = 0.480). Intravenous administration of nifedipine does not improve the patency of microvascular anastomosis. Surgical technique remains the most important factor for successful microvascular anastomosis.     

A prospective clinical evaluation of the effects of intraoperative systemic anticoagulation in patients undergoing arteriovenous fistula surgery

No standard presently exists for the use of systemic heparin during angioaccess surgery to decrease the incidence of postoperative thrombotic complications. Our objective was to study the effects of intraoperatively administered heparin on 30-day patency and postoperative bleeding complications in patients undergoing autogenous arteriovenous (AV) fistula surgery. A prospective, double-blinded, randomized controlled study was performed on 48 patients undergoing AV fistula creation from April 2007 through November 2009. Of the 48 patients, 22 were randomized to the control group and received no heparin. Twenty-six were randomized to receive heparin (75 units/kg intravenously) before clamping of the artery. There was no significant difference in 30-day patency between the heparin and control groups (92% vs. 86%, P = 0.65), respectively. Three patients (12%) developed hematomas in the heparin group compared with one (5%) in the control group; however the difference was not statistically significant (P = 0.61). The results suggest that intraoperative administration of heparin has no statistically significant effect on 30-day patency rates or postoperative bleeding complications. Larger trials with longer term follow-up and assessment of maturation rates are needed to determine the effect of intraoperative anticoagulation on these outcomes of arteriovenous fistula surgery.     

Comparative study of isovolemic hemodilution with 3% albumin, dextran-40, and prophylactic enoxaparin (LMWH) on thrombus formation at venous microanastomosis in rats

The objective of the present investigation was to compare the effect of isovolemic hemodilution with 3% albumin, dextran-40, and enoxaparin on the prevention of thrombosis in femoral vein microanastomosis using an experimental model in rats. Forty male Wistar rats were allocated into four groups: group 1, control, thrombogenic model without previous treatment; group 2, hemodiluted, thrombogenic model with previous hemodilution; group 3, dextran-40, thrombogenic model with dextran infusion (10 ml/kg), and group 4, enoxaparin, thrombogenic model with administration of enoxaparin (0.5 mg/kg/day). Hemostatic parameters, hematologic examinations, patency of anastomosis, and histopathological examination were evaluated. The hemostatic parameters were similar in the four groups studied. Group hemodiluted, dextran-40, and enoxaparin showed significantly reduced number of red blood cells and platelets as compared with the control group. The hemodilution significantly increased the patency rates of the vein at 20 min and 48 h. Dextran-40 and enoxaparin improved the patency of the vein only at 20 min, but failed to show a significant increase in the final patency at 48 h. After 48 h, the rate of venous thrombosis, as evaluated microscopically, was significantly decreased in hemodiluted animals (1/8) as compared with controls (10/10); in rats treated with dextran-40 (7/10) and enoxaparin (5/10) the rate of venous thrombosis was significantly higher as compared with rats of the group hemodiluted. Based on these observations, it can be concluded that hemodilution with albumin 3% was a safe and more adequate procedure than the use of the schemes of administration of dextran-40 and enoxaparin used in this study to prevent thrombus formation at femoral vein microanastomosis in rats. Since hemodilution promotes reduction in blood viscosity and in erythrocyte and platelet aggregation as well as dilution of the coagulation factors themselves, its use could provide better microcirculatory blood perfusion, decreasing the risk of thrombosis, and making possible safer microsurgical procedures.     

Dosage and timing of Photofrin for photodynamic therapy of intimal hyperplasia

Photodynamic therapy has been recommended as a method of preventing intimal hyperplasia. The purpose of this study was to determine the dose and timing of Photoftin porfimer sodium needed to achieve a 3:1 or higher ratio between injured and control arteries after balloon endothelial injury. New Zealand White rabbits were anesthetized and their right femoral artery surgically exposed. A 4Fr Fogarty balloon catheter was passed retrograde into the lower abdominal aorta, inflated and pulled distally into the external iliac artery six times. All rabbits received heparin 100 IU/kg. Arteriotomies were closed and the animals recovered. Rabbits (n = 5 per group) were given intravenous Photofrin at a dose and time according to the following scheme: group I, 5.0mg/kg immediately after balloon injury; group II, 2.5mg/kg immediately after injury; group III, 5.0 mg/kg after 1 week; group IV, 5.0 mg/kg after 2 weeks; or group V, 2.5 mg/kg after 2 weeks. Animals were killed 24 h after drug administration and the aortoiliac segments removed for spectrophotofluorometric determination of Photofrin levels from injured and control segments. Mean(s.d.) ratios of injured: control arteries for groups I to V were 4.8 (2.6), 2.8 (1.2), 3.0 (1.0), 1.4 (0.3) and 1.0 (0.0) respectively. This ratio was significantly higher for group I rabbits compared with groups IV and V (P< 0.01, ANOVA). Fluorescence and light microscopy showed that Photofrin was localized primarily in the tunica media, and that the drug must be administered before significant intimal hyperplasia occurs. This study suggested that the Photofrin dose of 5 mg/kg given immediately or within 7-days of injury achieved at least a 3:1 ratio between injured to control arterial segments. Ratios based on this dose were significantly higher than those from rabbits who received Photofrin 2 weeks after endothelial injury.     

Acute cyclosporin A renal dysfunction in dogs reversed by calcium antagonists and antiplatelet agents.

The aim of this study was to assess the effect of nifedipine and piracetam alone or in combination in the protection of renal function and morphology after cyclosporin A (CyA) administration. Thirty healthy mongrel dogs with a mean body weight of 15 kg were sacrificed. Six animals (group C) were given CyA 20 mg/kg body weight per os, while the remaining groups (8 animals each) were given concomitantly 20 mg nifedipine (group CN) or 4 g of piracetam (group CP), or both drugs in combination (group CNP). After 5 days of drug administration the animals were anesthetized, both kidneys were exposed, and functional tests were performed. Then the kidneys were removed for histological study. The mean plasma CyA levels in the four groups were 1765 +/- 685 ng/mL, 1300 +/- 324 ng/mL, 1116 +/- 491 ng/mL and 1600 +/- 290 ng/mL, respectively. Urine volume, creatinine, urea, and osmolar clearances were significantly higher in the groups CN, CP, and CNP compared to the control group C (p < 0.01). Urine sodium concentration was significantly higher (p < 0.05 or p < 0.01) in nifedipine groups than in the other two groups of animals, while the fractional excretion of sodium (FENa%) was significantly higher (p < 0.01) in all treated groups compared to controls. Plasma thromboxane-B2 levels were significantly reduced by each drug alone or in combination (p < 0.01). Morphological lesions, similar in all groups, did not correlate with the functional improvement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of donor treatment with heparinoids on graft function after intraportal transplantation of a marginal islet mass: an experimental study

Heparinoids interact with factors that are involved in ischemia-reperfusion injury and thus may prevent organ injury. We therefore studied the effects on subsequent intraportal islet transplantation of systemic administration of unfractionated and N-desulphated heparin to donors prior to pancreatectomy. Donor rats were given an intravenous injection of either heparin (1.3 mg/kg or 13.3 mg/kg; 200 U/kg or 2000 U/kg, respectively) or N-desulphated heparin (50 mg/kg; approximately 5 U/kg) at 5 to 10 minutes prior to pancreas procurement. Five hundred freshly isolated islets were injected intraportally into syngeneic male Lewis recipients that had developed streptozotocin-induced diabetes. Blood glucose and body weight were monitored for 5 weeks thereafter. Rats transplanted with islets from donors given high dose heparin showed a fall in blood glucose from 25.1 +/- 1.4 to 11.0 +/- 2.7 mmol/L (P <.01) with 60% of animals euglycemic within the first week. In contrast, the controls, did not show a fall in glucose levels at 1 week and none had become euglycaemic. Normalization of glycemia was slower in recipients of islets from animals treated with the lower dose of heparin. Results were intermediate with islets from donors given N-desulphated heparin. Nevertheless, all heparinoids used in this study caused more than a doubling of the number of animals achieving normoglycemia by 3 to 4 weeks. We hypothesize that pretreatment of the donor with heparin protects islet integrity during procurement and isolation and hence accelerates islet engraftment and remodelling. Since the effect was seen with N-desulphated heparin, which has negligible anticoagulant properties, we believe the mechanism to be independent of the anticoagulant activity.