A constant temperature perfusion system for myocardial energetics.

A constant temperature perfusion system employing four heat exchangers has been developed in which perfusion fluid is heated from room temperature to 37 +/- 10 -4 degrees C for precision heat flow measurements on isolated working rat hearts. The temperature characteristics have been established and mathematical expressions developed to identify and quantify spurious thermal events. The system is a refinement of existing perfusion systems for metabolic and mechanical investigations which meets the complete requirements of myocardial energetics. It can also be used for experiments which include high precision temperature measurements on isolated working hearts or for thermal investigations on other isolated perfused organs where a highly stabilised temperature base line is required over perfusion flows from 0-100 cm3 min -1.