Effects of low doses of esmolol on cardiac and vascular function in experimental septic shock

Abstract

Background: Administration of a selective β1-blocker, such as esmolol, in human septic shock has demonstrated cardiovascular protective effects related to heart rate reduction. Certain experimental data also indicate that esmolol exerts systemic anti-inflammatory and beneficial effects on vascular tone. Thus, the present study aimed to determine whether a non-chronotropic dose of esmolol maintains its protective cardiovascular and anti-inflammatory effects in experimental septic shock. Methods: Four hours after cecal ligation and puncture (CLP), Wistar male rats were randomly allocated to the following groups (n=8): CLP, CLP+E-1 (esmolol: 1mg.kg1.h1), CLP+E-5 (esmolol: 5mg.kg1.h1), CLP+E-18 (esmolol: 18mg.kg1.h1). An additional eight rats underwent sham operation. All rats received a continuous infusion of saline, analgesic and antibiotics 4hours after the surgery. Assessment at 18hours included in vivo cardiac function assessed by echocardiography and ex vivo vasoreactivity assessed by myography. Circulating cytokine levels (IL-6 and IL-10) were measured by ELISA. Cardiac and vascular protein expressions of p-NF-ΚB, IΚBα, iNOS, p-AKT/AKT and p-eNOS/eNOS were assessed by western blotting. Results: CLP induced tachycardia, hypotension, cardiac output reduction, hyperlactatemia and vascular hypo-responsiveness to vasopressors. Compared to CLP animals, heart rate was unchanged in CLP+E-1 and CLP+E-5 but was reduced in CLP+E-18. Stroke volume, cardiac output, mean arterial pressure and lactatemia were improved in CLP+E-1 and CLP+E-5, while vascular responsiveness to phenylephrine was only improved in CLP+E-5 and CLP+E-18. Plasma IL-6 levels were decreased in all esmolol groups. p-NF-ΚB was decreased in both cardiac and vascular tissues in CLP+E-5 and CLP+E-18. Conclusion: In experimental septic shock, low doses of esmolol still improved cardiac function and vasoreactivity. These benefits appear to be associated with a modulation of inflammatory pathways.