On Circulatory Control Mechanisms in the Pacific Hagfish

Publisher Website
Google Scholar
Abstract
Studies on the California hagfish have shown that its main (branchial) heart is without neural connections of any kind but factors controlling its action have not been made clear. Live specimens of the animal were appropriately prepared and the response of the branchial ventricle (isolated, as well as in situ) to change in return volume was studied. The chamber invariably responds to increased return by increase in force of contraction and is capable of developing systolic pressure of over 30 mm. Hg (from 0.5 mm. Hg resting). Ampullary hearts (portal and caudal) are both concerned with altering venous return. Caudal heart is reflexly controlled. Epinephrine has very little effect on the branchial ventricle. Reserpine slows and may depress it. In conclusion, the hagfish ventricle is controlled in vitro and in vivo by Starling''s Law or its equivalent without direct intervention of neural factors. The latter are imposed solely on venous hearts and affect the branchial ventricle solely by affecting venous return.