Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: Morphology and physiology of smooth muscle in the tunicate Ciona intestinalis, with emphasis on the role of external calcium in contractile activity
Student Author(s): Nevitt, Gabrielle A. Diablo
Faculty Advisor(s): Gilly, William F.
Pages: 17
Location: Final Papers Biology 175H
Date: June 1981
Keywords: ascidians
Abstract: We report here on the longitudinal body wall muscles of Ciona intestinalis using standard morphological and physiological methods. The muscle cells are arranged in long parallel bundles which are easily dissected and rapidly contract in response to electrical stimulation. Relaxation is slow. Activation of action potentials and twitches are critically dependant on external Ca, whereas extracellular Na shows no effect on excitability. Contractile response to depolarization via action potentials or KCL application dissappears at similar rates upon application of Ca free solutions. Our results do not support the existence of intracellular stores of releasable Ca and suggest that Ca influx is the sole source of activator Ca.