Ultrastructural Characteristics of Atrial, Ventricular and Subendocardial (Purkinje) Cells of the Fruit-Eating Bat <i>Eidolon helvum</i>

Abstract

The ultrastructure of the myocardium of the large (285 gm) fruit-eating bat (Eidolon helvum) provides further evidence that, among mammalian species, different types of cardiac myocytes are morphologically heterogeneous. Atrial cells of this species, like those of smaller bats previously studied, have few of the natriuretic hormone-containing granules. These granules are also small, with a mean diameter of 176 ± 3.9 nm in comparison with those of the rat (230 ± 5.8 nm) and mouse (211 ± 4.7 nm). In all types of myocytes of the bat investigated, mito-chondrial matrix granules are more prominent than in those of the rat and mouse. Also distinctive are the Purkinje cells which, aside from their large size (30 µm) and lack of T-tubules, have atrial granule-like inclusions. These cells are well endowed with mitochondria (28% of cytoplasmic volume) and with lipid bodies but have few glycogen granules. Their myofibrillae (33%) are well aligned. The ventricular cells (average diameter 14 µm) have nearly equal volumes of mitochondria (41%) and myofibrils (47%). Mitochondrial cristae, however, are not compactly organized. Lipid material is found in the matrix of the mitochondria. Extensive evaginations of endothelial cells of the bat endocardium appear continuous with endothelial vacuoles. In these endothelial cells, there are also many dense granules of varying shapes and sizes.

Demonstration of Atrial Natriuretic Peptide Immunoreactivity and Ultrastructurally Related Secretory Granules in Myoblasts of the Chick Myotome

“…1964;Newman et al, 1991] and in extra-atrial tissues [Gutkowska and Nemer. 1989;Ayettey et al, 1993], On the other hand, tak ing into account their size and morphology, these vesicles differ from the ones described by other authors, not only at the phase of myoblast but also at the collective phases of the histogenesis of the skeletal muscle (promyoblast, myo blast, myotube and myofibre) [Ezerman and Ishikawa, 1967;Ishikawa, 1968;Schiaffino and Hanzlikova. 1972;Tomanck and Colling-Saltin, 1977],…”

Papel del estrés oxidativo y nitrosativo en la hipertrofia cardiaca y remodelación ventricular

“…Esta tasa suele incrementarse durante la isquemia y aun más durante la isquemia acoplada con reperfusión (30)(31)(32). Estas condiciones tienen alto impacto en el corazón dado que hasta el 40% del volumen de los cardiomiocitos es ocupado por mitocondrias (40,41). El átomo de oxígeno contiene dos electrones no apareados en su orbita externa, y es por tanto altamente reactivo.…”