ELECTROGRAM OF ISOLATED PAPILLARY MUSCLE OF THE CAT HEART

Abstract

Using papillary muscle from the right ventricle of the cat''s heart, the electrogram was recorded when the muscles were contracting vigorously spontaneously or upon stimulation and were well-oxygenated. This electrogram is monophasic having a fast negative component ("R") followed by a slow deflection in the same direction ("T"). Absolute anoxia (reduction in available O2) or relative anoxia (increased rate of stimulation) both cause inversion of the T deflection. Decreasing temp. prolongs R and T deflections (Q10 = 2) and increases the amplitude and duration of contractions. The effect of digitoxin, HgCl2 and sym-pathomimetic amines was found to be similar to the actions noted in the ecg.