Coronary Drainage In the Octopus-vulgaris Systemic Heart

The vascular architecture of the coronary system of the systemic heart of the octopus (Octopus vulgaris) has been studied by means of both the corrosion-cast method and scanning electron microscopy. It is shown that the Octopus systemic heart myocardium is supplied through a very rich capillary network, the complexity of which probably reflects the complex organization of the ventricular wall. Drainage occurs by way of a classic venous system that originates from this capillary network. Morphological evidences are reported indicating that the coronary bed communicates directly with the ventricular lumen. In the isolated perfused systemic heart, the flow through this system is related directly to cardiac contractility. In an in situ preparation of the systemic heart, where for the first time simultaneous records have been obtained, ventricular pressure, coronary vein pressure, and coronary flow appear to be time related. It is suggested that in Octopus the venous coronary flow is not dependent on the systemic arterial pressure, as in the vertebrate heart, but it is directly dependent on intraventricular pressure.