Author + information
- Received July 13, 2009
- Revision received October 21, 2009
- Accepted November 2, 2009
- Published online March 9, 2010.
- ↵⁎Reprint requests and correspondence:
Dr. John D. Parker, University Health Network, Division of Cardiology, Mount Sinai and University Health Network Hospitals, 600 University Avenue, Suite 1609, Toronto, Ontario M5G 1X5, Canada
Objectives The purpose of this study was to determine whether single-dose rosuvastatin (40 mg) protects against ischemia and reperfusion (IR)–induced endothelial dysfunction in humans and whether this effect is cyclooxygenase (COX)-2 dependent.
Background Animal studies have demonstrated that rosuvastatin can limit damage and improve recovery after IR.
Methods In a double-blind, parallel design, 20 volunteers were randomized to a single dose of oral rosuvastatin (40 mg) or placebo. Twenty-four hours later, endothelium-dependent, flow-mediated dilation (FMD) of the radial artery was measured before and after IR (15 min of upper arm ischemia followed by 15 min of reperfusion). In a separate protocol, 18 volunteers received the COX-2 inhibitor celecoxib (200 mg orally twice daily) for 5 days. On day 4, subjects were randomized to single-dose rosuvastatin (40 mg) or placebo and 24 h later underwent the same protocol as described.
Results Pre-IR FMD was similar between groups (p = NS). IR significantly blunted FMD in the placebo group (FMD pre-IR: 6.4 ± 1.4%; FMD post-IR: 1.1 ± 3.8%, [p = 0.002]). Rosuvastatin prevented this impairment (FMD pre-IR: 7.5 ± 3.1%; FMD post-IR: 6.2 ± 3.9%, [p = NS] vs. rosuvastatin pre-IR, [p = 0.03] vs. placebo). Pre-treatment with celecoxib completely abolished rosuvastatin's protective effect (FMD pre-IR: 8.0 ± 2.2%; FMD post-IR: 1.4 ± 2.0%, [p < 0.001] compared with pre-IR, [p = NS] vs. placebo, [p = 0.002] vs. rosuvastatin alone).
Conclusions Rosuvastatin pharmacologically prevents the development of IR-induced conduit artery endothelial dysfunction. This beneficial effect of rosuvastatin is mediated by a COX-2–dependent mechanism, evidence that may also provide potential mechanistic insight into the reported cardiotoxic effects of COX-2 inhibitors.
- 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor
- ischemia reperfusion
The goal of therapy in patients with a myocardial infarction is timely and effective reperfusion to the infarcted area. Unfortunately, reperfusion itself can contribute to myocardial damage, a phenomenon called ischemia and reperfusion (IR) injury (1,2). Importantly, endothelial cells are particularly susceptible to and actively participate in this IR injury (3,4). Damaged and dysfunctional endothelium reduces perfusion to areas of previous ischemia and can exacerbate tissue injury, contributing to subsequent organ damage (5). Thus, the endothelium is a major determinant of the capacity of tissue to recover from IR, and interventions capable of protecting the endothelium from IR should be considered of direct clinical interest.
Exposure to brief periods of ischemia (ischemic preconditioning) can reduce myocardial and vascular sensitivity to IR-induced injury (5,6). Importantly, studies have demonstrated that certain pharmacological agents that target important effectors of the ischemic pre-conditioning pathway can mimic this phenotype (7,8): agents such as sildenafil (9) and nitroglycerin (10) have been shown to prevent IR-induced endothelial damage, an effect termed pharmacological pre-conditioning. 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have also been demonstrated to have such a preconditioning response in animal models (11–14). This protective phenotype has been shown to involve several mechanisms and mediators, including up-regulation of the cyclooxygenase (COX)-2 enzyme (15–17). Whether a similar protective phenotype occurs in humans in vivo and whether its manifestation is COX-2 dependent remain uninvestigated.
The Mount Sinai Hospital Research Ethics Board approved this investigator-initiated, non–industry-funded study, and all subjects gave informed consent. Study procedures are described in detail in previous publications from our group (9,10).
Protocol 1: effect of rosuvastatin on IR-induced conduit artery endothelial dysfunction
Twenty healthy nonsmoking volunteers (18 to 33 years of age) were enrolled in a double-blind, randomized, placebo-controlled, parallel trial. On the first study visit, standing blood pressure measurements were obtained followed by venous blood sampling for baseline lipid analysis. Subjects were then randomized to receive placebo or 40 mg rosuvastatin. Twenty-four hours after drug administration, standing blood pressure and plasma lipid measurements were repeated. Subsequently, radial artery flow-mediated dilation (FMD) was measured as previously described (9,10,18). After this measurement was completed, a pneumatic cuff placed above the antecubital fossa was inflated to 250 mm Hg for 15 min to induce local ischemia. The cuff was then deflated, and 15 min of reperfusion were allowed before FMD was measured again. We elected not to test endothelium-independent vasodilators because previous studies already demonstrated that this cycle of IR specifically impairs endothelium-dependent responses (5).
Protocol 2: effect of celecoxib pre-treatment
Eighteen healthy nonsmoking volunteers (18 to 33 years of age) were enrolled in a double-blind, randomized, placebo-controlled, parallel trial. After consent and baseline measurements as in protocol 1, subjects were administered celecoxib, a selective COX-2 inhibitor, 200 mg twice daily for 5 days. On day 4, subjects were randomized to receive a single dose of placebo or 40 mg rosuvastatin as in protocol 1. Twenty-four hours after randomization, subjects underwent FMD measurements before and after IR as described previously.
Data are presented as mean ± SD. Within-group comparisons were performed with a paired t test. Between-group differences and the interaction of IR and randomization group were studied with a 2-way analysis of variance. Post hoc comparisons were performed using the Bonferroni correction. A p value of <0.05 was set as the threshold for significance. SAS version 9.1.3 (SAS Institute Inc., Cary, North Carolina) was used for all statistical analyses.
Effect of rosuvastatin and celecoxib administration on baseline parameters
There were no significant differences in resting blood pressure, resting radial artery diameter, baseline blood flow, reactive hyperemia, or pre-IR FMD between groups in either protocol (Table 1).
Protocol 1: effect of placebo and rosuvastatin administration on IR-induced endothelial dysfunction
In both the placebo and the rosuvastatin groups, resting radial artery diameter and radial artery blood flow returned to baseline values 15 min post-IR (Table 1). Similarly, peak reactive hyperemia was not significantly different post-IR (Table 1). IR significantly blunted FMD in the placebo group (Fig. 1) (pre-IR: 6.4 ± 1.4%; post-IR: 1.1 ± 3.8%, p = 0.002). In contrast, rosuvastatin administration prevented the impairment in FMD associated with IR (Fig. 1) (pre-IR: 7.5 ± 3.1%; post-IR: 6.2 ± 3.9%, [p = NS] vs. FMD pre-IR, [p = 0.002] vs. placebo, [p = 0.03] for the interaction of IR and group).
Protocol 2: effect of celecoxib pre-treatment on rosuvastatin-mediated protection
As in protocol 1, resting arterial diameter, radial artery blood flow, and peak reactive hyperemia were not modified by IR in the celecoxib + placebo and the celecoxib + rosuvastatin groups (Table 1). IR significantly blunted FMD responses in the subjects who received celecoxib + placebo (Fig. 2) (pre-IR: 8.1 ± 1.9%; post-IR: 2.2 ± 2.8%, p < 0.001). Similarly, in the subjects who received celecoxib + rosuvastatin, IR blunted FMD to values similar to those observed in the placebo group of protocol 1 (Fig. 2) (pre-IR: 8.0 ± 2.2%; post-IR: 1.4 ± 2.0%, [p < 0.001] vs. FMD pre-IR, [p = NS] vs. celecoxib + placebo group, [p = 0.04] for overall group effect, [p = 0.004] for the interaction of IR and group, [p = 0.002] vs. rosuvastatin group in protocol 1).
Effect of rosuvastatin and celecoxib administration on lipid parameters
There were no significant differences in total cholesterol, high-density lipoprotein, low-density lipoprotein, or triglycerides between groups nor was there a significant difference in lipid parameters after the 24-hour period of treatment with rosuvastatin, celecoxib, or placebo in either protocol (Table 2).
The present study demonstrates, for the first time in humans, the ability of the HMG-CoA reductase inhibitor rosuvastatin to create an endothelial pharmacological pre-conditioning effect in the setting of IR injury at the level of the conduit vasculature. This effect seems to be mediated by a COX-2–dependent mechanism and is independent of reductions in plasma lipids. Our results are consistent with evidence from animal models of ischemic injury that have consistently demonstrated the ability of HMG-CoA reductase inhibitors to decrease infarct size, maintain vascular function, and improve functional recovery after IR injury (11,12,19–22).
We observed a significant blunting of FMD after IR in the placebo group, whereas the administration of rosuvastatin prevented this effect. Studies in animals suggest that the mechanism leading to such pre-conditioning–mimetic properties of HMG-CoA reductase inhibitors is likely multifactorial with up-regulation in the activity of ecto-5′ nucleotidase (an enzyme responsible for the production of adenosine) and of the endothelial and inducible isoforms of nitric oxide synthase believed to play a role (16,20,23). In addition, specific importance has been given to the induction of COX-2 activity, which is believed to depend on a HMG-CoA reductase inhibitor–mediated increase in nitric oxide bioavailability from both endothelial and inducible nitric oxide synthase sources (16,17). Our study demonstrates that the endothelial protection afforded by rosuvastatin is abolished in the presence of COX-2 inhibition, suggesting that COX-2 is at least partially involved in the signaling cascade leading to rosuvastatin-mediated protection in humans. To our knowledge, the current study represents the first demonstration of the importance of COX-2 in a human in vivo pre-conditioning model. This observation may have further clinical implications because it may contribute to the clarification of the mechanisms behind the observed increases in cardiovascular morbidity and mortality in patients receiving COX-2 inhibitors (24–26).
The fact that the present data were acquired in healthy volunteers and in a circulation that is different from the coronary circulation needs to be acknowledged. Additionally, the assessment of IR-induced endothelial dysfunction was limited to the conduit circulation and not to the distal microcirculation, a vascular bed that is also of importance in clinical IR injury. As mentioned earlier, previous studies have shown the IR injury used here specifically impairs endothelium-dependent responses while leaving endothelium-independent reactivity unaltered (5). Therefore, the fact that reactive hyperemia, a predominantly endothelium-independent process (27), is unimpaired in the present study should not be unexpected.
We demonstrate that rosuvastatin administration exerts potent endothelial protection against IR injury in conduit vessels via activation of COX-2. These results represent the first human evidence of a direct endothelial pharmacological pre-conditioning effect by rosuvastatin and may provide a mechanistic explanation to previous observations from clinical settings (13,14). Further, our data suggest a possible mechanistic explanation for the negative cardiovascular side effects of COX-2 inhibitors observed in clinical trials (24–26).
The authors thank the staff of the Mecklinger and Posluns Cardiac Catheterization Research Laboratory at Mount Sinai Hospital, Toronto, Ontario, Canada.
This study was funded by a grant from the Heart and Stroke Foundation of Canada. Dr. Parker holds a Career Investigator Award from the Heart and Stroke Foundation of Ontario, Toronto, Ontario, Canada.
- Abbreviations and Acronyms
- flow-mediated dilation
- 3-hydroxy-3-methylglutaryl coenzyme A
- ischemia and reperfusion
- Received July 13, 2009.
- Revision received October 21, 2009.
- Accepted November 2, 2009.
- American College of Cardiology Foundation
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