Meeting Abstract
30.2 Wednesday, Jan. 5 The function of trabeculae in the accessory heart wall of squid BARBANO, Duane L.*; NISHIKAWA, Kiisa C. ; UYENO, Theodore A. ; Northern Arizona University db356@nau.edu
An interesting question arises in surveying the diverse morphologies of hearts: Why is there so much variation in the three-dimensional structure of the luminal surface of the heart wall? These surfaces range from smooth to extremely rough because of the variable presence of trabeculae among species. Trabeculae are muscular ties that can connect portions of the heart wall together and that can extend out into the lumen. There are a number of functional hypotheses for the trabeculation of the heart wall: 1) the roughness of the heart wall may reduce suction that could impair heart filling; 2) trabeculae allow metabolically active muscle to be bathed in the blood of the heart lumen; and/or 3) muscles arranged as trabeculae may better cause tension to prevent heart valves from prolapsing. In this study, we hypothesize that the trabeculae may function as tunable elastic elements that store and return energy between pressure pulses. We describe the trabecular morphology of the paired accessory hearts of the Jumbo squid (Dosidicus gigas) and developed postulates of their function. We chose this model system for three reasons: 1) these hearts are highly trabeculated, 2) the hearts must expand elastically when filled by the central heart, and 3) they may represent an evolutionary response to low peripheral blood pressure. We described the morphology of the accessory hearts of seven adult squid by gross dissection and serial microtomy followed by Milligan’s trichrome staining to differentiate muscle and connective tissues. We found that accessory hearts bear a trabecular geometry that maximize their lengths, at the cost of decreasing the luminal diameter. It is possible this increases the amount of trabecular material in which elastic energy may be stored between pressure pulses. Supported by NAU TRIF Fund for Biotechnology.
