ISSN:
1432-136X
Keywords:
Key words Harbour porpoise
;
Metabolic rate
;
Ventilation
;
Aerobic dive limit
;
Blood oxygen binding
;
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
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003600050001
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