Comparative study of the arterial and lacunary systems of the ventricular myocardium of elasmobranch and teleost fishes

Abstract

The typical fish heart has a spongy trabeculated ventricular myocardium (spongiosa) supplied by the venous blood of the intertrabecular spaces (lacunae); hence it is called a "venous heart." However, in some fishes a more complex ventricular muscle is found (mixed type), in which the spongiosa is covered by an outer layer of densely arranged myocardial bundles (compacta). The compacta receives oxygenated blood from the coronary vessels. The objective of this study was to investigate relations between myoarchitecture and blood supply with an emphasis on the hitherto unexplored, putative vascular connections between the arterial and the lacunary circuits. Using histological methods combined with vascular cast techniques and India ink injections, it was possible to define four different types of ventricular myocardium and its microvasculature. In some of them an intramural network arises from the subepicardial arterial system supplying the compacta and also is distributed to the spongiosa. Extensive arterio-luminal vessels connect this coronary bed with the lacunary circuit of the spongiosa, so realizing the first evolutionary step of the Thebesian system. The highest development of these connections is found in some very active pelagic fishes. The functional morphology of these vascular patterns is discussed in relation to the phylogenetic and functional context of the fish heart. It appears that the concept of the piscine heart as a typical "venous" type is an oversimplified generalization, at least on morphological grounds.

Cardiac plasticity in fishes: environmental influences and intraspecific differences

“…These data suggest that the relationship between hypoxic adaptation and preconditioning in the trout heart resembles that of the neonatal/immature, not adult, mammalian heart. It is tempting to associate myocardial preconditioning with myocardium that is supplied with blood from the coronary circulation because the rat heart becomes increasingly dependent on its coronary circulation as it ages, and rainbow trout possess a coronary circulation (Tota et al, 1983) that supplies blood to the compact myocardium, which comprises the outer one-third of the heart (Fig.·5). However, the hypoxiasensitive heart of Atlantic cod Gadus morhua, which lacks a coronary circulation and is composed entirely of spongy myocardium, can be preconditioned (A. G. Genge and A. K. Gamperl,unpublished;Fig.·6) in much the same way as rainbow trout (Gamperl et al, 2001).…”

Phospholamban S-nitrosylation modulates Starling response in fish heart

“…It is interesting to note we have previously documented that in the eel A. anguilla heart, used as a paradigm of a highly trabeculate and endoluminally supplied cardiac design (Tota et al 1983), a basal release of endogenous NO increases the sensitivity of the Frank-Starling response (Imbrogno et al 2001). These studies using avascular working heart preparations, including the amphibian heart (Sys et al 1997), showed that this effect cannot be attributed to a rise in coronary flow or to factors released from vascular tissues.…”

Growing the coronary tree: The quail saga

“…Instead, if an increase in myocardial mass is desired, the heart muscle is organized into a spongy meshwork of trabeculae. The same arrangement of myocardium can be found even in some lower vertebrates, typically cold-blooded, relatively sedentary animals with low blood pressure, notably some fish (Ostadal and Schiebler, 1971;Tota et al, 1983) and amphibian species such as Xenopus, that has a coronaryless ventricle, although with rudimentary coronary vessels supplying the atrioventricular canal and the arterial pole .…”