TY - JOUR
T1 - Developmental changes in impulse conduction in the canine heart
AU - Rosen, M. R.
AU - Legato, M. J.
AU - Weiss, R. M.
PY - 1981
Y1 - 1981
N2 - We studied the age-related changes that occur in conduction in Purkinje fiber bundles (PF) from adult and 8-wk-old dogs. As PF are stretched, conduction velocity increases to a maximum when bundle length is ~1.5 times control. Conduction velocity in adult PF was significantly faster than that in 8-wk PF at all bundle lengths, the maximum being 2.32 ± 0.45 m/s (mean ±SD) in adult and 1.56 ± 0.59 m/s in 8-wk-old dogs. At >1.5 times control length, conduction velocity decreased, as did resting potential, action potential amplitude, and upstroke velocity. At 1.5 times control length, the ratio of PF to collagen in the bundles increased, and structural changes consistent with both unbuckling and unfolding of the cell membranes were seen. At greater degrees of stretch, cleft size diminished, and intracellular edema was noted. In sum, structural changes in cardiac PF can explain the changes in conduction velocity that occur with stretch. At all degrees of stretch, however, velocity is faster in PF from adult than from young dogs.
AB - We studied the age-related changes that occur in conduction in Purkinje fiber bundles (PF) from adult and 8-wk-old dogs. As PF are stretched, conduction velocity increases to a maximum when bundle length is ~1.5 times control. Conduction velocity in adult PF was significantly faster than that in 8-wk PF at all bundle lengths, the maximum being 2.32 ± 0.45 m/s (mean ±SD) in adult and 1.56 ± 0.59 m/s in 8-wk-old dogs. At >1.5 times control length, conduction velocity decreased, as did resting potential, action potential amplitude, and upstroke velocity. At 1.5 times control length, the ratio of PF to collagen in the bundles increased, and structural changes consistent with both unbuckling and unfolding of the cell membranes were seen. At greater degrees of stretch, cleft size diminished, and intracellular edema was noted. In sum, structural changes in cardiac PF can explain the changes in conduction velocity that occur with stretch. At all degrees of stretch, however, velocity is faster in PF from adult than from young dogs.
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M3 - Article
SN - 0363-6135
VL - 9
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4
ER -