Effects of statins on myocardial and coronary artery response to ischemia-reperfusion

Vasoreactivity of the Murine External Jugular Vein and Carotid Artery

INTRODUCTION

Impaired venous reactivity has potential to contribute to clinically significant pathologies such as arteriovenous fistula (AVF) maturation failure. Vascular segments commonly used in murine preclinical models of AVF include the carotid artery and external jugular vein. Detailed descriptions of isometric procedures to evaluate function of murine external jugular vein ex vivo have not been previously published.

OBJECTIVE

To establish isometric procedures to measure naive murine external jugular vein reactivity ex vivo.

METHODS

Vasomotor responses of external jugular veins and ipsilateral common carotid arteries from C57BL/6 mice were evaluated using isometric tension procedures.

RESULTS

External jugular veins developed tension (p < 0.05) to potassium chloride and U-46619, but not to phenylephrine, whereas common carotid arteries responded to all 3 agents (p < 0.05). While maximal responses to acetylcholine (ACh) were similar between the venous and arterial segments, the dose required to achieve this value was lower (p < 0.05) in the artery versus vein. Nitric oxide synthase inhibition attenuated (p < 0.05) but did not abolish ACh-evoked vasorelaxation in both vascular segments, whereas cyclooxygenase blockade had no effect. Endothelium-independent vasorelaxation to sodium nitroprusside was similar in the artery and vein.

CONCLUSION

Vasorelaxation and vasocontraction can be reliably assessed in the external jugular vein in C57BL/6 mice using isometric procedures.

Effect of Continuous-Flow Left Ventricular Assist Device Support on Coronary Artery Endothelial Function in Ischemic and Nonischemic Cardiomyopathy

Background:

The coronary vasculature encounters a reduction in pulsatility after implementing durable continuous-flow left ventricular assist device (CF-LVAD) circulatory support. Evidence exists that appropriate pulsatility is required to maintain endothelial cell homeostasis. We hypothesized that coronary artery endothelial function would be impaired after CF-LVAD intervention.

Methods and Results:

Coronary arteries from patients with end-stage heart failure caused by ischemic cardiomyopathy (ICM; n=16) or non-ICM (n=22) cardiomyopathy were isolated from the left ventricular apical core, which was removed for the CF-LVAD implantation. In 11 of these patients, paired coronary arteries were obtained from an adjacent region of myocardium after the CF-LVAD intervention (n=6 ICM, 5 non-ICM). Vascular function was assessed ex vivo using isometric tension procedures in these patients and in 7 nonfailing donor controls. Maximal endothelium-dependent vasorelaxation to BK (bradykinin; 10 − 6 –10 − 10 M) was blunted ( P <0.05) in arteries from patients with ICM compared with non-ICM and donor controls, whereas responses to sodium nitroprusside (10 −4 –10 −9 M) were similar among the groups. Contrary to our hypothesis, vasorelaxation responses to BK and sodium nitroprusside were similar before and 219±37 days after CF-LVAD support. Of these patients, an exploratory subgroup analysis revealed that BK-induced coronary artery vasorelaxation was greater ( P <0.05) after (87±6%) versus before (54±14%) CF-LVAD intervention in ICM patients, whereas sodium nitroprusside–evoked responses were similar.

Conclusions:

Coronary artery endothelial function is not impaired by durable CF-LVAD support and in ICM patients appears to be improved. Investigating coronary endothelial function using in vivo approaches in a larger patient population is warranted.

Pravastatin improves risk factors but not ischaemic tolerance in obese rats

Statins are effective in management of dyslipidaemia, and a cornerstone of CVD prevention strategies. However, the impacts of their pleiotropic effects on other cardiovascular risk factors and myocardial responses to infarction are not well characterised. We hypothesised that pravastatin treatment in obesity improves lipid profiles, insulin-resistance and myocardial resistance to ischaemia/reperfusion (I/R) injury. Wistar rats were fed a control (C) chow or high carbohydrate and fat diet (HCFD) for 16 weeks with vehicle or pravastatin (prava 7.5 mg/kg/day) treatment for 8 weeks. At 16 weeks HOMAs were performed, blood samples collected and hearts excised for Langendorff perfusions/biochemical analyses. Anti-oxidant activity and proteins regulating mitochondrial fission/fusion and apoptosis were assessed. The HCFD increased body weight (736±15 vs. 655±12 g for C; P<0.001), serum triglycerides (2.91±0.52 vs. 1.64±0.26 mmol/L for C; P<0.001) and insulin-resistance (HOMA- 6.9±0.8 vs. 4.2±0.5 for C; P<0.05) while prava prevented diet induced changes and paradoxically increased lipid peroxidation. The HCFD increased infarct size (34.1±3.1% vs. 18.8±3.0% of AAR for C; P<0.05), which was unchanged by prava in C and HCFD animals. The HCFD decreased cardiac TxR activity and mitochondrial MFN-1 and increased mitochondrial DRP-1 (reducing MFN-1:DRP-1 ratio) and Bax expression, with the latter changes prevented by prava. While unaltered by diet, cytosolic levels of Bax and caspase-3 were reduced by prava in C and HCFD hearts (without changes in cleaved caspase-3). We conclude that obesity, hyper-triglyceridemia and impaired glycemic control in HCFD rats are countered by prava. Despite improved risk factors, prava did not reduce myocardial infarct size, potentially reflecting its complex pleiotropic impacts on cardiac GPX activity and MFN-1, DRP-1, caspase-3 and Bcl-2 proteins.

Loss of the preconditioning effect of rosuvastatin during sustained therapy: a human in vivo study

Studies have demonstrated that the acute administration of 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has protective effects in the setting of ischemia-reperfusion (IR). Previously, we demonstrated that a single dose of rosuvastatin prevented IR-induced endothelial dysfunction in humans through a cyclooxygenase-2-dependent mechanism. Whether the chronic administration of HMG-CoA reductase inhibitors provides similar protection remains controversial and is unknown in humans. Eighteen male volunteers were randomized to receive a single dose of rosuvastatin (20 mg) or placebo. Twenty-four hours later, endothelium-dependent, radial artery flow-mediated dilation (FMD) was measured before and after IR (15 min of upper arm ischemia followed by 15 min of reperfusion). In a separate protocol, 30 healthy volunteers were randomized in a double-blind fashion to receive oral rosuvastatin (20 mg/day) and placebo, rosuvastatin, and celecoxib (100 mg bid) or placebo alone, all for 21 days. Twenty-four hours after the final administration of study medication, FMD was measured before and after IR. Pre-IR FMD was similar between groups in both protocols. In the acute administration protocol, rosuvastatin significantly prevented the blunting of FMD associated with IR (FMD pre-IR: 8.4 ± 1.3%; post-IR: 6.2 ± 1.3%; P = 0.01 ANOVA, treatment group interaction). In the daily administration protocol, IR significantly blunted FMD in the placebo group (FMD pre-IR: 7.5 ± 0.9%; post-IR: 3.3 ± 0.7%; P < 0.001). Chronic treatment with rosuvastatin did not modify this ischemic injury (FMD pre-IR: 6.9 ± 0.4%; post-IR: 1.6 ± 1.0%; P < 0.001; P = NS ANOVA, treatment group interaction). Similarly, FMD responses post-IR in volunteers receiving rosuvastatin and celecoxib did not significantly differ from placebo (FMD pre-IR: 8.3 ± 0.9%; post-IR: 2.1 ± 0.8%; P < 0.001; P = NS ANOVA, treatment group interaction). In contrast to acute administration, chronic rosuvastatin does not prevent the development of IR-induced endothelial dysfunction in normal humans.

Gastric antisecretory and antiulcer effects of simvastatin in rats

BACKGROUND AND AIM

Recently, statins have appeared to have additional benefits beyond their lipid lowering effects, which has led to the interest in the use of this class of drugs outside the realm of cardiovascular disease. Simvastatin (SIM) is a commonly prescribed statin with anti-inflammatory and antioxidant properties. Excessive generation of oxygen-derived free radicals (ODFR) and proinflammatory mediators has been implicated in the pathogenesis of gastric ulcers. This investigation aimed to study the effect of SIM on experimentally induced gastric acid secretion and ulcer formation.

METHODS

Adult Wistar rats were divided into experimental groups containing six animals. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with SIM (20, 40, and 60 mg/kg). The effect of orally administered SIM was also studied on indomethacin- and ethanol-induced gastric ulcers. The levels of myeloperoxidase (MPO), non-protein sulfhydryls (NP-SH), nitric oxide (NO), antioxidant enzymes, and gastric wall mucus were measured in the glandular stomach of rats following ethanol-induced gastric lesions.

RESULTS

Administration of SIM significantly and dose-dependently inhibited the volume of gastric secretion and the acidity. Pretreatment with SIM significantly reduced the formation of indomethacin- and ethanol-induced gastric lesions. The antiulcer activity of SIM was associated with significant attenuation of adverse effects of ethanol on gastric wall mucus, NP-SH and MPO. SIM modified the gastric NO levels and reversed the ethanol-induced decrease in glutathione-S-transferase and increase in superoxide dismutase and catalase.

CONCLUSIONS

These findings clearly suggest the involvement of proinflammatory agents and ODFR in the pathogenesis of gastric lesions. The gastroprotective effects of SIM are mediated by inhibition of neutrophils activity, reduction of oxidative stress, and maintenance of vascular integrity. This study was conducted in rats; its relevance to human gastric ulcers is not known and warrants further study.

Influence of preoperative lipid-lowering therapy on postoperative outcome in patients undergoing coronary artery bypass grafting

Statin therapy has recently been shown to decrease adverse perioperative events in patients undergoing vascular surgery. The potential beneficial effect of lipid-lowering therapy in patients undergoing coronary artery bypass grafting (CABG) is not well known. This was an observational analysis of 4,739 patients who underwent first-time isolated CABG at a single institution from 1995 to 2001. Patients were categorized into 2 groups based on treatment with a lipid-lowering agent within 30 days before surgery. Univariate and multivariate analyses were used to determine the association between lipid-lowering therapy and survival to hospital discharge. Patients in the lipid-lowering group (n = 2,334) tended to be younger (mean age 66 +/- 10 vs 68 +/- 10 years), were more likely to be diabetic (31% vs 28%), and on beta blockers (77% vs 70%) than patients in the nonlipid-lowering group (n = 2,405). In-hospital mortality was significantly lower in the lipid-lowering group than in the nonlipid-lowering therapy group (1.4% vs 2.2%, odds ratio 0.62, 95% confidence interval 0.40 to 0.96, p = 0.03). A multivariable model demonstrated a loss of statistical significance for the effect of lipid-lowering therapy on in-hospital mortality (adjusted odds ratio 0.83, 95% confidence interval 0.5 to 1.37, p = 0.46). In conclusion, preoperative use of lipid-lowering therapy in patients undergoing CABG appears safe and is associated with improved survival to hospital discharge compared with patients not receiving lipid-lowering therapy. However, patient risk factors and other cardioprotective medication use associated with the use of preoperative lipid-lowering therapy appear to explain the association with improved survival.

Preoperative statin use and outcomes following cardiac surgery

BACKGROUND

Cardiac surgery carries a 2-3% early mortality due in part to perioperative myocardial infarction (PMI), low-output syndrome (LOS), and arrhythmias. Statins attenuate thrombogenesis, normalize endothelial dysfunction, and mitigate the oxidative stress and reperfusion injury characteristic of such complications. We sought to determine whether preoperative statin use is associated with reduced early mortality and major morbidity following cardiac surgery.

METHODS

Patients having isolated coronary artery bypass grafting (CABG), valve, or combined CABG/valve surgery between May 1998 and June 2003 (n=5469) were identified. A logistic regression model was generated to determine the association of preoperative statin use with in-hospital mortality (IHM). Propensity score analysis was used to match two subgroups of patients (Group I, on statins, n=1443; Group II, not on statins, n=1443) on multiple factors known to impact cardiac surgical outcome. Outcomes assessed were IHM, intra-aortic balloon pump (IABP) use, PMI, prolonged (>24 h) ventilation (p-vent), stroke, and a composite end point (comp) defined as any one or more of the above.

RESULTS

Of the 5469 patients, 3555 were on statins and 1914 were not. Unadjusted rates of IHM (2.6% vs. 5.0%), stroke (1.9% vs. 3.3%), p-vent (10.2% vs. 16.6%), and comp (12.7% vs. 19.5%) were lower (p=0.0001) in patients receiving statins. After adjustment, statin use was not associated with a reduction in IHM (OR=0.9, 95% CI=0.6-1.2, p=0.36) or comp (OR=0.9, 95% CI=0.8-1.1, p=0.31). After matching two subgroups using propensity score for statin, no significant differences were found in any of the adjusted outcomes for Group I vs. Group II: IHM (4.0% vs. 4.6%), PMI (1.5% vs. 1.1%), p-vent (15.8% vs. 15.7%), IABP use (2.0% vs. 2.3%), stroke (3.0% vs. 3.3%), and comp (19.1% vs. 18.8%).

CONCLUSIONS

Preoperative statin use is not associated with a reduction in IHM or major morbidity following cardiac surgery.