Lack of direct coronary vascular effects of Escherichia coli endotoxin in dogs

This study explored the hypothesis that coronary vascular injury and dysfunction result from intracoronary administration of Escherichia coli endotoxin (0.025 to 0.025 to 0.4 mg/kg) in dogs. Peak hyperemic coronary flow following a 15-sec period of stopped flow and the maximum flow in response to adenosine were used to estimate coronary vascular reserve. The wet-to-dry ratio of myocardial tissue was used to estimate extravascular water content as an indicator of vascular leak due to endothelial injury. Intracoronary saline was used as a control. Peak reactive hyperemia and maximum flow at constant coronary pressure were not different in the animals receiving intracoronary endotoxin (n = 6) and the animals receiving saline (n = 5) during 4 hr following treatment. In addition, wet-to-dry ratios were similar in these two groups. These data fail to support the hypothesis that endotoxin, per se, produces coronary vascular injury of sufficient magnitude to produce myocardial dysfunction.