Related Experiment Video
Updated: Jul 4, 2026
Lipopolysaccharide Infusion as a Porcine Endotoxemic Shock Model
Published on: December 8, 2023
Endothelin-Dependent Myocardial Dysfunction in an Experimental Endotoxic Shock Model
Mustafa Boz1, Alper Bektaş İskit1
1Department of Pharmacology, Hacettepe University, Faculty of Medicine, Ankara, Türkiye.
Objective:
Impaired myocardial contractility is a major contributor to cardiovascular failure during septic shock; however, the underlying mechanisms remain incompletely understood. This study investigated the roles of endothelin and nitric oxide (NO) in cardiac dysfunction using the endothelin receptor antagonist tezosentan and nitric oxide synthase (NOS) inhibitors in an experimental model of endotoxic shock.
Method:
Endotoxic shock was induced in rats via intraperitoneal injection of lipopolysaccharide (LPS, 1 mg/kg). Hearts were isolated four hours after LPS or saline administration and perfused using a Langendorff apparatus. Myocardial contractility, coronary perfusion pressure, and heart rate were recorded. The effects of tezosentan and NOS inhibitors (Nω-nitro-L-arginine methyl ester [L-NAME], aminoguanidine, and S-methylisothiourea sulfate [AETU]) were assessed by adding these agents to the perfusate. In parallel, atrial and papillary muscle contractility and spontaneous beating rates were evaluated using isolated tissue preparations in in vitro organ bath studies.
Results:
Baseline myocardial contractility was significantly reduced in LPS-treated perfused hearts compared with controls (3.03 +- 0.25 vs. 4.94 +- 0.39 g, P < 0.05), whereas no significant differences were observed in isolated atrial or papillary muscle preparations. Coronary perfusion pressure was significantly increased in the LPS group (101 +- 6 vs. 79 +- 6 mmHg, P < 0.05). Tezosentan significantly attenuated the LPS-induced reduction in myocardial contractility but did not affect the increase in perfusion pressure. None of the NOS inhibitors altered myocardial contractility or perfusion pressure in LPS-treated hearts.
Conclusion:
Myocardial contractility impairment in experimental endotoxic shock occurs only in the presence of an intact coronary vasculature and is prevented by endothelin receptor blockade. These findings suggest that vascular endothelium-derived endothelin plays a key role in myocardial depression during endotoxic shock, whereas nitric oxide appears to have a limited contribution in this model.
Insights
Endotoxemia impairs heart function by increasing endothelin, not nitric oxide. Blocking endothelin receptors improved cardiac contractility in this septic shock model.
Area of Science:
- Cardiovascular Physiology
- Septic Shock Pathophysiology
- Endothelial Function
Background:
- Septic shock frequently leads to cardiovascular failure due to impaired myocardial contractility.
- The precise mechanisms underlying this cardiac dysfunction remain unclear.
- Endothelin and nitric oxide (NO) pathways are implicated in cardiovascular regulation.
Purpose of the Study:
- To investigate the roles of endothelin and nitric oxide in cardiac dysfunction during experimental endotoxic shock.
- To evaluate the therapeutic potential of endothelin receptor antagonism and nitric oxide synthase inhibition.
Main Methods:
- Endotoxic shock was induced in rats using lipopolysaccharide (LPS).
- Isolated perfused hearts and cardiac muscle preparations were used to assess myocardial contractility.
- The effects of tezosentan (endothelin receptor antagonist) and NOS inhibitors were evaluated.
Main Results:
- LPS significantly reduced myocardial contractility in perfused hearts but not in isolated muscle preparations.
- Tezosentan attenuated the LPS-induced decrease in contractility.
- Nitric oxide synthase inhibitors did not affect myocardial contractility or coronary perfusion pressure.
Conclusions:
- Myocardial depression in endotoxic shock is dependent on an intact coronary vasculature.
- Endothelin, released from the vascular endothelium, plays a critical role in myocardial dysfunction during endotoxic shock.
- Nitric oxide has a limited role in this septic shock model.
