We have investigated the effect of acidosis on the ECG in isolated rat hear
t to determine whether acidosis has marked effects on the ECG, and have use
d pharmacological agents to investigate possible mechanisms whereby acidosi
s alters the ECG. Acidosis produced a marked decrease in heart rate and an
increase in P-R interval with little apparent effect on the duration of the
QRS complex. The effects of acidosis did not appear to be due to acidosis-
induced changes in transmitter release from severed autonomic nerve termina
ls within the heart.