Rome L C, Syme D A, Hollingworth S, Lindstedt S L, Baylor S M
Department of Biology, University of Pennsylvania, Philadelphia 19104, USA.
Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):8095-100. doi: 10.1073/pnas.93.15.8095.
Vertebrate sound producing muscles often operate at frequencies exceeding 100 Hz, making them the fastest vertebrate muscles. Like other vertebrate muscle, these sonic muscles are "synchronous," necessitating that calcium be released and resequestered by the sarcoplasmic reticulum during each contraction cycle. Thus to operate at such high frequencies, vertebrate sonic muscles require extreme adaptations. We have found that to generate the "boatwhistle" mating call (approximately 200 Hz), the swimbladder muscle fibers of toadfish have evolved (i) a large and very fast calcium transient, (ii) a fast crossbridge detachment rate, and (iii) probably a fast kinetic off-rate of Ca2+ from troponin. The fibers of the shaker muscle of rattlesnakes have independently evolved similar traits, permitting tail rattling at approximately 90 Hz.
脊椎动物的发声肌肉通常以超过100赫兹的频率运作，使其成为脊椎动物中最快的肌肉。与其他脊椎动物肌肉一样，这些发声肌肉是“同步的”，这就要求在每个收缩周期中，钙由肌浆网释放并重新摄取。因此，为了在如此高的频率下运作，脊椎动物的发声肌肉需要极端的适应性变化。我们发现，为了发出“汽笛”般的求偶叫声（约200赫兹），蟾鱼的鱼鳔肌纤维已经进化出了以下特点：（i）大且非常快速的钙瞬变；（ii）快速的横桥解离速率；（iii）可能还有钙离子从肌钙蛋白上快速的动力学解离速率。响尾蛇的尾部颤动肌纤维也独立进化出了类似的特性，使得其尾部能以约90赫兹的频率颤动。
