In 1887 some unusual characteristics were noted in the contractile properties of tortoise atria that became known as “oscillations of tonus”. The oscillations were later found to be present in the turtle atria, and believe to be caused by a layer of endocardial smooth muscle. Since 1925, there has been no further published interest in these oscillations. In this study, histological and immunohistochemical staining techniques were used to confirm the presence of endocardial smooth muscle, and contractile studies were used to further characterise its properties. Atrial tissue was isolated from the red eared slider turtle (Trachemys scripta), and contractile responses to adrenaline, acetylcholine and wortmannin were recorded. Tissue was also embedded in paraffin and stained using haematoxylin & eosin stain, or was labelled using smooth muscle α-actin monoclonal antibodies. Results from these studies will be considered in relation to earlier findings and the significance of the smooth muscle layer in the reptile myocardium will be discussed.
37th Congress of IUPS (Birmingham, UK) (2013) Proc 37th IUPS, PCB085
Poster Communications: Smooth Muscle in Turtle Atrial Myocardium: Functional and Histological Evidence
S. N. Saxton1, J. Stecyk2, B. Gannon3, T. Farrell4, H. Shiels5
1. Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom. 2. Department of Biological Sciences, University of Alaska, Anchorage, Alaska, United States. 3. Department of Anatomy and Histology, Flinders University, Adelaide, South Australia, Australia. 4. Faculty of Land and Food Systems and Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada. 5. Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
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Where applicable, experiments conform with Society ethical requirements.