Campbell Hamish A, Egginton Stuart
Department of Physiology, University of Birmingham, PO Box 363, Edgbaston, Birmingham, B15 2TT, UK.
J Exp Biol. 2007 Jul;210(Pt 14):2472-80. doi: 10.1242/jeb.003822.
The extent and efficiency of cardio-respiratory coupling (CRC) in teleost fishes is unclear. We simultaneously monitored heart rate (fH) and ventilation rate (fV) in Paranotothenia angustata, and applied modern power spectral analysis (PSA) mathematics to examine the rate association under varying levels of oxygen consumption (MO2). At low MO2 (0.94 mmol O2 kg(-1) h(-1)) there was a correspondingly low fH and fV (25.5+/-2.4 min(-1) and 29.2+/-2.6 min(-1), respectively). Heart rate variability (HRV) consisted of oscillatory components caused by periodic vagal inhibition of the heart beat. Cross-spectral analysis showed that fH and fV were coupled, with the response lag in heart beat being approximately one seventh of each ventilation cycle. Ingestion of food elevated MO2 (1.99+/-0.02 mmol O2 kg(-1) h(-1)) and increased both fH and fV (45+/-2.3 min(-1) and 52+/-2 min(-1), respectively, P<0.05), but CRC was maintained despite a reduction in HRV. The elevated stress caused by handling and placement of fish into respirometry chambers raised fH and fV to a similar rate as observed after feeding, although high-frequency (>0.2 Hz) oscillations in fH were lacking and MO2 was lower (1.82+/-0.03 mmol O2 kg(-1) h(-1), P<0.05). Subsequent cardiac vagotomy elevated fH and fV (55.5+/-0.8 min(-1) and 48.2+/-0.7 min(-1), respectively; P<0.05) but abolished all HRV and CRC, although MO2 was significantly less for a given fH and fV compared to intact fish. Thus, P. angustata exhibits vagally mediated CRC, and the association between fH and fV varies according to oxygen demand.
硬骨鱼类心脏呼吸耦合（CRC）的程度和效率尚不清楚。我们同时监测了狭体副南极鱼的心率（fH）和呼吸频率（fV），并应用现代功率谱分析（PSA）数学方法来研究不同耗氧量（MO2）水平下的频率关联。在低MO2（0.94 mmol O2 kg⁻¹ h⁻¹）时，fH和fV相应较低（分别为25.5±2.4 min⁻¹和29.2±2.6 min⁻¹）。心率变异性（HRV）由心跳周期性迷走神经抑制引起的振荡成分组成。互谱分析表明fH和fV是耦合的，心跳的反应延迟约为每个呼吸周期的七分之一。摄食使MO2升高（1.99±0.02 mmol O2 kg⁻¹ h⁻¹），并使fH和fV均增加（分别为45±2.3 min⁻¹和52±2 min⁻¹，P<0.05），尽管HRV降低，但CRC仍得以维持。将鱼处理并放入呼吸测量室所引起的应激增加使fH和fV升高至与摄食后相似的速率，尽管fH中缺乏高频（>0.2 Hz）振荡且MO2较低（1.82±0.03 mmol O2 kg⁻¹ h⁻¹，P<0.05）。随后的心脏迷走神经切断术使fH和fV升高（分别为55.5±0.8 min⁻¹和48.2±0.7 min⁻¹；P<0.05），但消除了所有HRV和CRC，尽管与完整鱼相比，在给定的fH和fV下MO2显著降低。因此，狭体副南极鱼表现出迷走神经介导的CRC，并且fH和fV之间的关联根据氧气需求而变化。
