The Effects of Substrates on Contractility of Isolated Human Atria 1

Abstract

Summary

Isolated strips cut from the right atrial appendage of 7- to 10-year-old patients undergoing cardiac surgery were placed in Krebs-Ringer bicarbonate medium at 37° and stimulated at 70 pulses per min. If the medium contained 5.5 mM glucose as substrate, the force of contraction declined rapidly. Contractility could be maintained at a constant level for 6 hr with 20 mM glucose. The optimal concentration of glucose, however, was 30 mM. Equilibration of atria in 30 mM glucose was followed by incubation in glucose-free medium for 30 min in another series and resulted in a marked fall in contractility. Introduction of 30 mM glucose or pyruvate resulted in a prompt and complete restoration of contractile force to control levels. Fructose, lactate, or acetate, also at 30 mM, restored the force only partially.