Power output of sound-producing muscles in the tree frogs Hyla versicolor and Hyla chrysoscelis.

摘要: Sound-producing muscles provide the opportunity of studying limits power production at high contractile frequencies. We used work loop technique to determine available from external oblique in two related species North American gray tree frog, Hyla chrysoscelis and versicolor. These trunk contract cyclically, powering high-intensity sound anuran amphibians. The H. have an vivo operating frequency 40–55 Hz 20–25 degrees C, whereas versicolor these with a temperatures. In investigations shown that use asymmetrical sawtooth length trajectory (with longer shortening phase compared lengthening phase) during natural cycles. To study influence this particular on output, we subjected both sinusoidal trajectories. species, yielded significantly higher output than pattern. maximum cycles was similar (54 W kg(−)(1) 58 versicolor). values are impressive, particularly frequencies temperatures muscle. only 60 % total (34 for 36 optimum cycle maximizing using pattern were approximately 44 21 close those by calling. Operating frequencies, maximized strain amplitude 8 value 12 strains match stimulus timing observed calling also yielding optimal (6 ms before start versicolor, respectively). As expected, twitch duration is much shorter (23 37 ms, There less remarkable difference between their velocities (V(max)) 13.6 L(0)s(−)(1) 11.1 where L(0) muscle length. force-velocity curves very flat, which increases output. At myofibrillar level, flat more compensate lower peak isometric force found muscles. data presented here emphasize importance incorporating variables designing vitro studies.