Effects of the aldosterone receptor antagonist potassium canrenoate on renal blood flow and urinary output during prolonged increased intraabdominal pressure (IAP) in pigs

Neutral Effects of Combined Treatment With GLP-1R Agonist Exenatide and MR Antagonist Potassium Canrenoate on Cardiac Function in Porcine and Murine Chronic Heart Failure Models

Background: Ischemia-reperfusion and cardiac remodeling is associated with cardiomyocyte death, excessive fibrosis formation, and functional decline, eventually resulting in heart failure (HF). Glucagon-like peptide (GLP)-1 agonists are reported to reduce apoptosis and myocardial infarct size after ischemia-reperfusion. Moreover, mineralocorticoid receptor antagonists (MRAs) have been described to reduce reactive fibrosis and improve cardiac function. Here, we investigated whether combined treatment with GLP-1R agonist exenatide and MRA potassium canrenoate could minimize cardiac injury and limit HF progression in animal models of chronic HF.

Methods and Results: Forty female Topigs Norsvin pigs were subjected to 150 min balloon occlusion of the left anterior descending artery (LAD). Prior to reperfusion, pigs were randomly assigned to placebo or combination therapy (either low dose or high dose). Treatment was applied for two consecutive days or for 8 weeks with a continued high dose via a tunneled intravenous catheter. Using 2,3,5-Triphenyltetrazolium chloride (TTC) staining we observed that combination therapy did not affect the scar size after 8 weeks. In line, left ventricular volume and function assessed by three-dimensional (3D) echocardiography (baseline, 7 days and 8 weeks), and cardiac magnetic resonance imaging (CMR, 8 weeks) did not differ between experimental groups. In addition, 36 C57Bl/6JRj mice underwent permanent LAD-occlusion and were treated with either placebo or combination therapy prior to reperfusion, for two consecutive days via intravenous injection, followed by continued treatment via placement of osmotic mini-pumps for 28 days. Global cardiac function, assessed by 3D echocardiography performed at baseline, 7, 14, and 28 days, did not differ between treatment groups. Also, no differences were observed in cardiac hypertrophy, assessed by heart weight/bodyweight and heart weight/tibia length ratio.

Conclusion: In the current study, combined treatment with GLP-1R agonist exenatide and MR antagonist potassium canrenoate did not show beneficial effects on cardiac remodeling nor resulted in functional improvement in a small and large animal chronic HF model.

Interactions of Enhanced Urocortin 2 and Mineralocorticoid Receptor Antagonism in Experimental Heart Failure

Background—

Mineralocorticoid receptor antagonists (MRAs) have become established therapy in heart failure (HF). Urocortin 2 (Ucn2) is a novel peptide with potential in the treatment of this disease. The present study investigated the interactions of acute administration of Ucn2 and an MRA in experimental HF.

Methods and Results—

Ucn2 and an MRA (canrenoic acid [CA]) were infused for 4 hours, both singly and together, in 8 sheeps with pacing-induced HF. Ucn2, when administered as an adjunct to CA, further improved hemodynamic indices relative to that achieved by CA alone, producing additional increases in cardiac output and decreases in left atrial pressure and peripheral resistance but without eliciting a supplementary reduction in arterial pressure. Ucn2 cotreatment reversed CA-induced rises in circulating aldosterone levels, and also significantly reduced plasma renin activity, angiotensin II, and vasopressin concentrations. Although both CA and Ucn2 infusion produced a diuresis and natriuresis, responses with Ucn2 and Ucn+CA were 2- to 3-fold greater than that elicited by separate CA. Ucn2 cotherapy additionally increased urine potassium and creatinine excretion. In contrast to the rise in plasma potassium induced by CA, Ucn2 cotreatment reduced potassium concentrations.

Conclusions—

Ucn2 cotreatment with an MRA in HF further improved hemodynamics relative to that achieved by CA alone, while also reducing plasma renin activity, angiotensin II, aldosterone and vasopressin levels, and enhancing renal function. Importantly, Ucn2 prevented CA-induced rises in plasma potassium. These data demonstrate a favorable profile of effects with short-term adjunct Ucn2 therapy and an MRA in HF.

The effects of high-frequency jet ventilation (HFJV) on pneumoperitoneum-induced cardiovascular changes during laparoscopic surgery

BACKGROUND

Standard mechanical ventilation may cause adverse cardiovascular effects in addition to those already related to positive-pressure pneumoperitoneum (PP) during laparoscopic surgery. High-frequency jet ventilation (HFJV) is associated with much less airway pressure, with potentially less influence on venous return, thus potentially it may reduce those effects. The aim of this study was to evaluate the benefits of HFJV to reduce the adverse cardiovascular effects during laparoscopic cholecystectomy.

METHODS

We conducted a randomized prospective trial, comparing 12 patients undergoing elective laparoscopic cholecystectomy under conventional mechanical ventilation (control) with 13 similar subjects under HFJV (study). Both groups were categorized as ASA I-II and underwent total intravenous anesthesia. Cardiac functionality was continuously evaluated by analysis of arterial pressure wave changes (Edwards Flo-Trac sensor and Vigileo monitor).

RESULTS

There was no significant difference between both groups regarding age, gender, BMI, and general medical condition, as well as hemodynamic stability and blood gases throughout surgery. A significant reduction in cardiac output was noted in the control group under PP during the initiation of anti-Trendelenburg position (from 5.6 to 5.0 l/min, P = 0.049). A reciprocal change was observed regarding stroke volume. Such changes were not noticed under HFJV. Total peripheral resistance was significantly increased during PP, and heart rate was not significantly affected throughout surgery in both groups. Unexpectedly, we did not observe marked adverse hemodynamic changes in the control group during PP without position adjustment.

CONCLUSIONS

The use of HFJV in upper laparoscopic surgery can impede the adverse cardiovascular changes that usually occur during induction of PP. We also suggest that the use of total intravenous anesthesia (as used in our study) may also lessen the cardiovascular impairment during PP.

Antioxidant prophylaxis for cellular injury in ovarian surface epithelium resulting from CO₂ pneumoperitoneum in a laparoscopic rat model

OBJECTIVE

Selective cytoprotective functions of vitamin E, N-acetyl-L: -cysteine, and amifostine have been used as a preventer of ischemia injury by expelling the free oxygen radicals leading to stabilization of the cellular membranes. The purpose of this experimental study was to investigate the oxidative stress related to cellular injury in ovarian surface epithelium and the effect of prophylaxis with an anti-oxidant using laparoscopic rat model.

DESIGN

Laparoscopic rat model.

MATERIALS AND METHODS

Randomly allocated 40 Wistar Albino female rats have been used for the pneumoperitoneum model which was constituted to fix the intraabdominal pressure on 5 mmHg for 60 min. The antioxidants, vitamin E and NAC were given to rats 3 days before the operation and were applied for 30 days; amifostine was applied 30 min before the operation until after for 7 days. After abdominal desufflation, over biopsies were made on the 13th min, 24th h, and 7th and 30th days. By using of transmission electron microscopy, the damage on cells and organels were assessed and graded.

RESULTS

In ovarian surface epithelium, the apical surface specializations were affected in all groups except Vit E group:The microvilli were irregular and coarse and had disappeared in some places. Some cells were separated from the epithelium. In addition, mitochondria degeneration was observed in all group except Vit E.

CONCLUSIONS

In the early period of laparoscopy, reversible cellular damage occurs and this damage can be prevented by vitamin E.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

Validation and reduction of the oxidative stress following laparoscopic operations: a prospective randomized controlled study

OBJECTIVE

To validate ischemia-reperfusion mechanism during laparoscopic cholecystectomy, and to assess the reduction of oxidative stress by an intermittent sequential pneumatic compression (ISPC) device.

SUMMARY BACKGROUND

Increased intraperitoneal pressure during laparoscopic operations may lead to decreased cardiac output and visceral perfusion, and possible ischemia-reperfusion effects. Using the ISPC device was shown to improve cardiac output and visceral perfusion during pneumoperitoneum (PP).

METHODS

Twenty patients undergoing elective laparoscopic cholecystectomy were enrolled in a randomized prospective controlled study and divided into 2 groups: 1) study group (10 patients), activation of ISPC together with creation of PP; and 2) control group, without ISPC. Lipid peroxidation and glutathione levels (as indicators of oxidative stress) as well as liver and renal function tests, were measured before and at the end of PP, and again at 30 minutes, 4 hours, and 24 hours afterward, together with hemodynamic and respiratory parameters.

RESULTS

There was no significant difference between both groups concerning liver enzymes and bilirubin, nor in hemodynamic parameters. In the control group, increased lipid peroxide levels were noted 4 hours after PP termination, in comparison to pre-PP levels (590.4-649.2 mmol/L, P = 0.002). In the study group (ISPC), such changes were not inspected. Decreased total glutathione levels were noted in the control group, 30 minutes following CO2 evacuation.

CONCLUSIONS

Our study validates the ischemia-reperfusion mechanism following laparoscopic surgery. The use of an ISPC device decreased the oxidative stress (secondary to relative ischemia-reperfusion insult) following PP, probably due to improved cardiac output and visceral perfusion.