Effects of endotoxin on coronary vascular resistance in the isolated blood-perfused rabbit heart.
Rabbit hearts were excised and perfused with blood pumped through a cannula placed in the aortic root. A fluid-filled balloon-tipped catheter was positioned in the left ventricle for the measurement of left ventricular pressure and dP/dt. Total coronary vascular resistance (CVR) was calculated by dividing the coronary perfusion pressure by the rate of coronary blood flow. Following stabilization, coronary blood flow was held at a constant rate. Compared to control hearts, endotoxin (E. coli) added directly to the blood perfusate (6 mg/80 ml of circulating blood) had no effect on CVR or left ventricular dP/dt. In contrast, changing the perfusate to blood obtained from rabbits previously given endotoxin (LD100; 6 mg/kg IV) resulted in significantly higher CVR, without depression of left ventricular dP/dt. This increase in CVR was observed not only when the endotoxemic donor rabbits were hypotensive at the time the blood was obtained (4-6 hours following endotoxin administration), but also when the endotoxemic donors remained normotensive (blood withdrawn 30 minutes following endotoxin administration). A pathologic increase in CVR might contribute to the myocardial ischemia and contractile dysfunction observed in endotoxin shock.
D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010477:Perfusion; D011817:Rabbits; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects*
D004731:Endotoxins