Cardiovascular Anesthesia
نویسندگان
چکیده
Hypertonic saline improves organ perfusion and animal survival during hemorrhagic shock because it expands plasma volume and increases tissue oxygenation. Because both decreased and increased myocardial performance have been reported with hypertonic saline, the effects of hyperosmolarity and the mechanism accounting for it were investigated in isolated blood-perfused rabbit hearts. Coronary blood flow (CBF), myocardial contractility, relaxation, and oxygen consumption were measured during administration of blood perfnsates containing 140-180 mm01 sodium concentrations ([Nat]). In two other series of experiments, the role of Na+-Cazt exchange in the inotropic effect of hyperosmolarity (160 mm01 sodium concentration) and hypertonicity (sucrose) were also investigated. Hypertonic [Nat] induced a significant increase in contractility and relaxation, combined with a coronary vasodilation. Myocardial oxygen consumption (Mvo,) increased at all hypertonic [Na+] without significant change in coronary venous oxygen tension (PvoJ and content (Cvo,). Amiloride (0.3 mmol) inhibited the improved contractility observed with 160 mmol sodium. Similar Nat-Ca” exchanger blockade did not inhibit the inotropic effect of sucrose. These results confirm the positive inotropic effect of hypertonic [Nat]. The inhibition of this improvement by amiloride suggests that calcium influx through the sarcolemna could be the major mechanism of this effect. (Anesth Analg 1995;81:777-82)
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