Department of Biology, University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Germany.
J Exp Biol. 2012 Jan 15;215(Pt 2):362-73. doi: 10.1242/jeb.063743.
In Calliphoridae and Drosophilidae, the dorsal vessel (heart and aorta with associated venous channels) is the only connection between the thorax and the abdomen. Hemolymph oscillates between the compartments by periodic heartbeat reversal, but both the mechanism and its influence on hemocoelic and tracheal pressure have remained unclear. The pumping direction of the heart regularly reverses, with a higher pulse rate during backward compared with forward pumping. A sequence of forward and backward pulse periods lasts approximately 34 s. Pulse rate, direction, velocity and the duration of heartbeat periods were determined by thermistor and electrophysiological measurements. For the first time, heartbeat-induced pressure changes were measured in the hemocoel and in the tracheal system of the thorax and the abdomen. The tracheal pressure changed from sub-atmospheric during backward heartbeat to supra-atmospheric during forward heartbeat in the thorax and inversely in the abdomen. The heartbeat reversals were coordinated with slow abdominal movements with a pumping stroke at the beginning of the forward pulse period. The pressure effect of the pumping stroke was visible only in the abdomen. Periodic hemolymph shift and abdominal movements resulted in pressure changes in the hemocoel and tracheal system alternating in the thorax and abdomen, suggesting an effect on respiratory gas exchange.
在丽蝇科和果蝇科中，背血管（心脏和主动脉以及相关的静脉通道）是胸部和腹部之间的唯一连接。血淋巴通过周期性心跳反转在隔室之间振荡，但心跳反转的机制及其对血腔和气管压力的影响仍不清楚。心脏的泵送方向定期反转，与向前泵送相比，向后泵送时脉冲率更高。大约 34 秒的时间内，正向和反向脉冲周期交替。通过热敏电阻和电生理测量来确定心跳周期的脉冲率、方向、速度和持续时间。首次测量了在胸部和腹部的血腔和气管系统中，由心跳引起的压力变化。在胸部，心跳反转期间，从向后心跳的亚大气压变为向前心跳的超大气压，而在腹部则相反。心跳反转与腹部缓慢运动协调，在正向脉冲周期开始时进行泵送冲程。泵送冲程的压力效应仅在腹部可见。周期性血淋巴转移和腹部运动导致血腔和气管系统中的压力变化在胸部和腹部交替，表明对呼吸气体交换有影响。
