Cardiac morphodynamic remodelling in the growing eel (Anguilla anguilla L.)

Abstract

The morphodynamic changes occurring during growth were evaluated in the eel (Anguilla anguilla L.) heart. Using an in vitro working heart preparation, cardiac performance of small (body mass 96.76±27.49·g; mean ± S.D.) and large (body mass 656±12·g; mean ± S.D.) eels was compared under basal conditions and under loading (i.e. preload and afterload) challenges. A parallel morphometric evaluation of the ventricle was made using light and transmission electron microscope images.The small eel hearts show a basal cardiac output lower than their large counterparts (heart rate fH, 38.93±2.82 and 52.7±1.8·beats·min -1 , respectively; stroke volume VS, 0.27±0.017 and 0.37±0.016·ml·kg -1 , respectively; means ± S.E.M.). The two groups show similar responses at increasing preload, but differ remarkably at increasing afterload. Small eel hearts decreased VS at afterload greater than 3·kPa, in contrast to larger hearts, which maintained constant VS up to 6·kPa. These changes in mechanical performance are related to structural differences.Compared with the small eels, the large eels show an increase in the compacta thickness and in the diameter of the trabeculae in the spongiosa, together with reduction of the lacunary spaces. The increased compacta thickness is attained by enlargements of both the muscular and vascular compartments and reduction of the interstitium; consequently, this layer appears more compacted. Both compacta and spongiosa show higher number of myocytes together with reduced cross-sectional area and myofibrillar compartment. The compacta also shows an increased mitochondrial compartment. Our results document a cardiac morphodynamic remodelling in the growing eel.

Cortisol response to stress is associated with myocardial remodeling in salmonid fishes

“…Fibrosis is the dominant histological reaction to injury in the mammalian heart and it adversely increases tissue stiffness and impairs normal cardiac function (Schnitt et al, 1993;Weber et al, 1994). In fish, though, collagen remodeling has been postulated to play an important role in the maintenance of mechanical cardiac performance (Cerra et al, 2004;Icardo et al, 2005). We also found enhanced collagen deposition in the HR ventricles compared with the LR ventricles, as evaluated by AFOG staining.…”

“…We found a higher expression of the angiogenic gene VEGF in the HR ventricles compared with the LR ventricles, which likely reflects the increased vascularization necessary to support the thicker layer of compact myocardium (Cerra et al, 2004), as this is the muscular layer vascularized by coronary vessels. Increased vascularization was indeed extensive when HR ventricles were visually examined.…”

“…For example, an increased ventricular mass in cold-acclimated rainbow trout serves to offset the reduction in cardiac power output observed with acute decreases in temperature, and also enhances stroke volume (Graham and Farrell, 1989). Also, in the growing eel (Anguilla anguilla L.), structural remodeling of the heart, such as growth of the compact myocardium, is associated with enhanced mechanical performance (Cerra et al, 2004). The calcium/calcineurin-regulated NFATc family is thought to have arisen following recombination approximately 500 million years ago, producing a new group of signaling and transcription factors (the NFATc genes) found only in genomes of vertebrates.…”

The heart ofSparus auratus: a reappraisal of cardiac functional morphology in teleosts

“…Ventricular performance must be finely adjusted to the varied hemodynamic challenges experienced by fish species according to their remarkably different ecophysiological and body plan characteristics. To what extent the impressive hemodynamic flexibility of fish cardiac performance is reflected in the architectural design of the ventricular chamber is an issue of elevated interest in comparative cardiac morphodynamics (Tota and Gattuso, '96;Cerra et al, 2004). In fish, two main types of ventricular myocardial organization are described, that is, the trabeculated and the compact myocardium.…”

The Teleost Heart: A Morphological Approach

“…The proportion of the compacta has been reported to vary with changing seasons (Farrell and Jones 1992 ) and growth (Farrell et al 1988 ;Cerra et al 2004 ) , but not with physical activity (Farrell et al 1990 ) . It should be mentioned that both the compacta and the spongiosa are formed by typical cardiomyocytes (Yamauchi 1980 ;Santer 1985 ;Cerra et al 2004 ;Icardo et al 2005b ) whose structural, functional, and metabolic characteristics have been reviewed a number of times through the years (Yamauchi 1980 ;Santer 1985 ;Farrell and Jones 1992 ;Burggren et al 1997 ) . The different morphological arrangements do not depend on distinct characteristics of the myocardial cells, but on the speci fi cs of the heart design.…”