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The cardiac muscle in the pulmonary vein of the rat: A morphological and electrophysiological study
Author(s) -
de Almeida Oslei Paes,
Böhm György Miklös,
Carvalho Marilene de Paula,
de Carvalho Antonio Paes
Publication year - 1975
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051450403
Subject(s) - anatomy , vasa vasorum , biology , pulmonary vein , cardiac muscle , cholinergic , electrophysiology , venous valves , vein , ultrastructure , acetylcholine , medicine , endocrinology , neuroscience , ablation
The pulmonary veins of albino Wistar rats were studied by means of light and electron microscopy. The media of larger veins consists of cardiac muscle fibers which extend until the vessels attain about 100 μ in diameter. This coat consists of external longitudinal fibers and internal circular fibers. The vasa vasorum are well developed and the capillaries show pseudofenestrations. The numerous adrenergic and cholinergic nerve endings do not form typical motor end‐plates as seen in skeletal muscles. The ultrastructure of these media muscle fibers is similar to that of rat hearts. The smooth muscle layer of larger pulmonary veins is not continuous as it is in smaller veins where it forms cushions. Comparisons of albino rats and other rodents reveal striking differences. Action potential shape and propagation velocity (0.5–1.2 m/s) along the myocardial coat of the pulmonary vein were similar to those observed in the left atrium and so was their sensitivity to locally applied acetylcholine. The physiological direction of propagation in rat pulmonary veins is toward the lung. This finding lends support to the hypothesis of a rhythmic, valve‐like action of the striated musculature of the pulmonary venous wall during the systole and a possible role in the capacitance of the pulmonary circulation.