Effects of nebivolol on ischemia-induced metabolic changes in dog hearts

The pretreatment of rats with nebivolol ameliorates bladder contractile dysfunction caused by ischemia-reperfusion injury

OBJECTIVE

The present study aimed to investigate the protective effect of nebivolol in the bladder isolated from rats exposed to ischemia-reperfusion (IR) injury.

METHODS

Sprague-Dawley rats were divided into control, IR, and nebivolol+IR groups. In the nebivolol+IR group, nebivolol was administered (0.4 mg/kg, subcutaneous) in rats prior to IR insult. At the end of the experimental protocol, the urinary bladder was rapidly isolated and bladder strips were mounted in an organ bath. After the equilibration period, potassium chloride (KCl, 20-100 mM) or carbachol (0.01-10 μM) was cumulatively added to the organ bath to generate cumulative concentration-response curves (CCRCs). Oxidative stress and interleukin 6 (IL-6) levels were also evaluated in the bladder tissue.

RESULTS

The CCRCs of KCl and carbachol were significantly reduced in the IR group compared to those of the control, and this inhibition was reversed by the pretreatment of rats with nebivolol (P < .05). The IR group's total antioxidant status was significantly lower with a concomitant increase in IL-6 levels than that of the control and nebivolol+IR groups (P < .05).

CONCLUSIONS

The present study indicates that pretreatment of rats with nebivolol (0.4 mg/kg) could improve bladder contractile dysfunction caused by IR injury through suppression of increased oxidative stress and IL-6 levels.

Nebivolol: new therapy update

Nebivolol is a beta-blocker under U.S. Food and Drug Administration review for the treatment of hypertension. The unique pharmacologic properties of nebivolol include high specificity for the beta-1 receptor and a nitric oxide-mediated vasodilatory effect. The agent provides significant blood pressure reduction from baseline values as compared with placebo. Clinical trials have demonstrated that nebivolol reduces blood pressure similarly to atenolol, bisoprolol, amlodipine, nifedipine, lisinopril, and hydrochlorothiazide. The tolerability of nebivolol is similar to or better than that of these agents. In elderly patients (> or = 70 years of age) with clinically stable congestive heart failure, the addition of nebivolol to the treatment regimen improved the time to all-cause mortality and cardiovascular hospital admissions over that of placebo. If approved, nebivolol would likely be a viable alternative therapy for hypertension and heart failure; however, additional studies are needed in patients having coronary artery disease.

Pharmacological Mechanisms of Clinically Favorable Properties of a Selective β1-Adrenoceptor Antagonist, Nebivolol

Nebivolol is a racemic mixture of d- and l-enantiomers. The drug is characterized by beta(1)-adrenoceptor selectivity and long-acting beta-blockade exerted predominantly by d-enantiomer. Nebivolol is devoid of intrinsic sympathomimetic activity and has no relevant membrane stabilizing action. Antiproliferative properties of nebivolol were demonstrated in endothelial and smooth muscle cell cultures. Infusion of nebivolol causes a vasodilation in all vascular beds by endothelial-dependent mechanism involving stimulation of beta(3)-adrenoceptors as well as by endothelial-independent mechanism. Nebivolol possesses not only direct vasodilator properties but also augments the action of endothelium-dependent vasodilators. The antioxidant property of nebivolol can at least in part explain why treatment with this drug enhances eNOS activity and minimizes the reperfusion-induced myocardial injury. The systemic effects of nebivolol in humans have an unusual hemodynamic profile. In contrast to traditional beta-adrenoceptor antagonists, nebivolol reduces preload and afterload due to systemic vasodilation and improves arterial distensibility. At 5 mg daily nebivolol effectively reduces systolic and diastolic blood pressure over a 24-h period. During treatment with nebivolol arterial pressure follows the natural circadian rhythm. Trough-to-peak ratio for nebivolol is 0.9. It has been demonstrated in numerous placebo-controlled studies that exercise tolerance is not reduced during nebivolol therapy. By chronic administration to patients with left ventricular dysfunction nebivolol increases myocardial contractility. Nebivolol produced no significant changes in lipid levels, insulin sensitivity or glucose tolerance. These findings make nebivolol a promising therapeutic tool for the treatment of arterial hypertension and chronic heart failure.