Abstract
The respiratory physiology, heart rates and metabolic rates of two captive juvenile male harbour porpoises (both 28 kg) were measured using a rapid-response respiratory gas analysis system in the laboratory. Breath-hold durations in the laboratory (12 ± 0.3 s, mean ± SEM) were shorter than field observations, although a few breath-holds of over 40 s were recorded. The mean percentage time spent submerged was 89 ± 0.4%. Relative to similarly-sized terrestrial mammals, the respiratory frequency was low (4.9 ± 0.19 breaths · min−1) but with high tidal volumes (1.1 ± 0.01 l), enabling a comparatively high minute rate of gas exchange. Oxygen consumption under these experimental conditions (247 ± 13.8 ml O2 · min−1) was 1.9-fold higher than predicted by standard scaling relations. These data together with an estimate of the total oxygen stores predicted an aerobic dive limit of 5.4 min. The peak end-tidal O2 values were related to the length of the previous breath-hold, demonstrating the increased oxygen uptake from the lung for the longer dives. Blood oxygen capacity was 23.5 ± 1.0 ml · 100 ml−1, and the oxygen affinity was high, enabling rapid oxygen loading during ventilation.
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Accepted: 11 August 1999
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Reed, J., Chambers, C., Hunter, C. et al. Gas exchange and heart rate in the harbour porpoise, Phocoena phocoena . J Comp Physiol B 170, 1–10 (2000). https://doi.org/10.1007/s003600050001
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DOI: https://doi.org/10.1007/s003600050001
- AbbreviationsADL aerobic dive limit
- BMR basal metabolic rate
- BTPS body temperature and pressure, saturated
- βNB non-bicarbonate buffering capacity
- CCO2 total CO2 concentration
- fH heart rate
- fR breathing frequency (breaths
- min−1)
- IHR instantaneous heart rate
- Mb body mass (kg)
- P50 the partial pressure of oxygen at which 50% of the haemoglobin is saturated with oxygen
- PO2 partial pressure of oxygen (kPa)
- PCO2 partial pressure of carbon dioxide (kPa)
- PEFR peak expiratory flow rate (l
- sec−1)
- PIFR peak inspiratory flow rate (l
- sec−1)
- RQ respiratory quotient
- Td breath-hold duration (s)
- Tex time for expiration (s)
- Tin time for inspiration (s)
- Ts surface time (s)
- Ttot total duration for one ventilation cycle (s)
- TLC total lung capacity (l)
- Ve minute volume (l
- min−1)
- Vt tidal volume (l)
- V˙O2 rate of oxygen consumption