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At least 721 records · Page 40Linked to original sources
PubMed1988

Alteration in vomeronasal system anatomy in alcelaphine antelopes: correlation with alteration in chemosensory investigation.

Ruminants typically have an incisive papilla and incisive ducts located on the hard palate just behind the dental pad which are involved in transferring fluid-borne stimulus material from the oral cavity to the vomeronasal organs (VNOs) during flehmen. This behavior in males is presumably involved in the detection of chemosensory cues in female urine which indicate sexual status. Two species of alcelaphine antelopes, topi and Coke's hartebeest, were found to lack the incisive papilla and incisive ducts constituting the oral connection to the VNOs. This distinctive anatomical feature is complemented in these species not only by lack of flehmen behavior, but also a de-emphasis on chemosensory interest in female urine during sexual encounters. The common wildebeest, which is also an alcelaphine antelope, lacks the incisive papilla, but has small incisive ducts. Wildebeest males do perform flehmen to urine from females. However, during flehmen in the wildebeest, intermittent nostril licking apparently delivers the stimulus material to the VNOs via the nasal route, possibly compensating for reduced oral access to the VNOs. These observations on alcelaphine antelopes would appear to represent a unique feature among the world's ruminants.

Animals↗
PubMed1976

O2 transport in the alpaca (Lama pacos) at sea level and at 3,300 m.

Five male alpacas native to high altitude, of approximately 40 kg, were studied first at 3,300 m and again after a 3-month sojourn at sea level. Measurements were made with the animals standing, unsedated and breathing air. Cardiac output was measured by the dye dilution technique. Blood gas tensions and contents were measured in arterial and mixed venous blood. Blood samples were also equilibrated with different oxygen tensions to construct O2-Hb dissociation curves. The P50 was 17.8 and 19.7 torr at 3,300 m and at sea level, respectively. The higher P50 values at sea level were associated with higher values of base excess. PaO2 was lower at 3,300 m but SaO2 was always above 90%. No significant changes in [Hb], Hct, Q, CaO2 and CvO2 with changes in elevation were observed. PaCO2 tended to be lower at altitude indicating a mild hyperventilation. The values of PvO2 were lower than those reported for other mammals but similar to those of the llama. A higher PvO2 was measured in the alpacas at sea level. The alpaca under conditions of chronic hypoxia presents only minor cardiorespiratory adjustments suggesting the possibility of tissue characteristics well suited for life at high altitude.

Adaptation, Physiological↗
PubMed1977

Blood respiratory properties of Bison bison.

The respiratory properties and basic hematology of blood from seven adult bison and one calf were determined. Average oxygen-carrying capacity was 22.2 ml/100 ml blood from adults and 17.0 in calf blood; hemoglobin averaged 17.1 g/100 ml in adults and 13.6 in the calf. Half saturation of the blood occurred at 32mm Hg Po2 at pH 7.40 and 37 degrees C. The average Bohr effect was -0.40. Erythrocytes numbered 8.6 X 10(6)/mm3 and were 52 micron 3 in mean volume. Adult and calf cells differed in mean cell hemoglobin, adults 19.9 pg/cell vs 15.9 in the calf, and this difference evidently caused differences in Haldane effect, standard bicarbonate, and buffering capacity. Bison are capable of prolonged running. Two features of the blood that promote this capacity are its comparatively great oxygen-carrying capacity and low oxygen affinity.

Age Factors↗
PubMed1978

Dead space and tidal volume of the giraffe compared with some other mammals.

The ventilation, tidal volume and anatomical dead-space were measured in a living giraffe and compared with similar measurements in a camel, red deer, llama and man. The giraffe had a resting tidal volume of about 3.3 litres with a dead-space/tidal-volume ratio of 0.34. The giraffe breathes slowly, apparently because of the unusually small diameter of its trachea relative to its length, compared with known measurement in other mammals.

Animals↗
PubMed1979

Nasal heat exchange in the giraffe and other large mammals.

The respiratory air of the giraffe is exhaled at temperatures substantially below body core temperature. As a consequence, the water content of the exhaled air is reduced to levels below that in pulmonary air, resulting in substantial reductions in respiratory water loss. Measurements under outdoor conditions showed that at an ambient air temperature of 24 degrees C, the exhaled air was 7 degrees C below body core temperature, and at ambient air temperature of 17 degrees C, the exhaled air was 13 degrees C below core temperature. The observations were extended to two additional species of wild and four species of domestic ungulates. All these animals exhaled air at temperatures below body core temperature. The average amount of water recovered due to cooling of the air during exhalation, calculated as per cent of the water loss that would occur if air were exhaled at body core temperature, amounted to between 24 and 58%, the average value for the giraffe being 56%.

Animal Population Groups↗
PubMed1981

Design of the mammalian respiratory system. III Scaling maximum aerobic capacity to body mass: wild and domestic mammals.

The purpose of this study was to determine whether the maximal rate of oxygen consumption (Vo2max) is scaled proportionally to Mb1.0, as the diffusing capacity of the lung, or proportionally to Mb0.75, as the standardized resting rate of oxygen consumption (V02std). We measured Vo2max on a variety of mammalian species (14 wild species and 8 domestic or laboratory species ranging in Mb from 7.2 g to 263 kg) using the same 'treadmill' procedure for all animals. For the wild species we found: Vo2max = 1.94.Mb0.79; r=0.995 where Vo2max has the units ml . sec-1 and mb is in kg. There was a great variability in Vo2max among domestic species of the same size, horse and dog having a Vo2max more than 3 times that of a cow and sheep, respectively. Both the variability in Vo2max with body size and among animals of the same size provide powerful tools for investigating the relationship between structure and function at each step in the respiratory system, from the oxygen in environmental air to the oxygen sink in the mitochondria.

Aerobiosis↗
PubMed1981

Design of the mammalian respiratory system. V. Scaling morphometric pulmonary diffusing capacity to body mass: wild and domestic mammals.

This paper utilizes a comparative approach to establish the relationship between morphometric diffusing capacity for oxygen (DLo2) and maximal oxygen consumption (Vo2max). DLo2 and Vo2max were determined on the same 21 individuals in African mammals spanning a range in body mass from 0.4 to 240kg. We confirmed earlier findings that Dlo2 was proportional to Mb0.99 while Vo2max was proportional to Mb0.79. Thus, the ratio of Dlo2/Vo2 is approximately proportional to Mb0.20. We conclude that large animals require a larger pulmonary diffusing capacity to transfer oxygen at the same rate from air to blood.

Aerobiosis↗
PubMed1981

Design of the mammalian respiratory system. VI Distribution of mitochondria and capillaries in various muscles.

The variability of structures supporting tissue oxygen transport (capillaries) and oxygen consumption (mitochondria) was analyzed in skeletal muscles of wildebeest and dik-dik. Regional differences in mitochondria and capillary densities within individual muscles were found for M. semitendinosus (twofold) but not for M. longissimus dorsi and diaphragm. Comparing 20 different muscles from both animals, the volume density of mitochondria in the muscle fibers [Vv(mt,f)] was significantly higher in diaphragm (10-12%) and varied considerably (1-6%) in the other muscles. The relation between Vv(mt,f) and the number of capillaries per cross-sectional fiber area NA(c,f) showed great variability. In glycolytic fibers Vv(mt,f) was typically low (1%) whereas in oxidative fibers it ranged from 5-15%. No systematic trend was found for the packing of cristae in subsarcolemmal and interfibrillar mitochondria from both types of fibers in large and small animals.

Animals↗
PubMed1981

Design of the mammalian respiratory system. VII. Scaling mitochondrial volume in skeletal muscle to body mass.

Since O2 is mainly consumed in muscle mitochondria during heavy physical work, one would expect to find a relationship between the volume density of mitochondria in skeletal muscles and maximal O2 uptake. We analyzed the volume density of mitochondria, Vv(mt,f) in four muscles of a series of African mammals ranging in body mass from 0.4 to 251 kg. Vv(mt,f) scaled as Mb-0.231, Mb-0.163, Mb-0.139 and Mb-0.055 in Mm. semitendinosus, longissimus dorsi, vastus medialis and diaphragm, respectively. The mass or volume of diaphragm was found to scale as Mb0.865, whereas for Mm. semitendinosus and vastus medialis, muscle volume (Vmu) scaled as Mb1.030 and Mb0.956 respectively. Scaling the absolute volume of mitochondria Vmt, in these muscles (Vmt = Vv (mt,f) x Vmu) against Mb gives regression lines whose slopes closely parallel that obtained for Vo2max against body mass. Therefore the ratio of volume of mitochondria in these muscles to Vo2max is body mass independent.

Africa↗
PubMed1981

Design of the mammalian respiratory system. VIII Capillaries in skeletal muscles.

The relationship between capillary density and mitochondrial volume density in skeletal muscle tissue is investigated on 25 African mammals ranging in body mass from 0.4 to 251 kg. As a general trend higher capillary densities, NA (c,f) are found in muscles with higher volume densities of mitochondria, Vv(mt,f). The individual data however show considerable scatter. Part of this scatter can be explained by the fact that NA (c,f) alone is not a sufficient parameter to account for functional properties of the vascular supply. The regional variability of the capillary network from arterial to venous end also contributes to the data spread. A number of physiological variables of the vascular compartment may also influence the relationship of capillary counts to the mitochondrial densities of muscle fibers. This relationship therefore cannot be expected to be a simple one.

Africa↗
PubMed1983

Metabolic meaning of elevated levels of oxidative enzymes in high altitude adapted animals: an interpretive hypothesis.

It is commonly observed that during acclimatization to altitude oxidative enzyme activities increase per g wet weight of tissue. To examine this problem in long-term adapted animals we measured citrate synthase (CS), hydroxyacylCoA dehydrogenase (HOAD), pyruvate kinase (PK), and lactate dehydrogenase (LDH) activities/g of myocardium in two domestic species (llama and alpaca) and a high altitude deer, the taruca. In all these species, we found an upward scaling of oxidative capacity (indicated by absolute activities of CS and HOAD) but a downward scaling of anaerobic/aerobic metabolic potentials of the heart (indicated by low ratios of LDH/CS, and LDH/HOAD, but high ratios of PK/LDH). As the direction and magnitude of these long-term adaptations are the same as in shorter-term acclimatizations, we wondered why a similar pattern at the enzyme level correlates with the right shift of the O2 dissociation curve (ODC) in the latter case, but with a left shifted ODC in the former. We hypothesize that in the long term, increased oxidative enzyme activities allow increased maximum flux capacity of aerobic metabolism. This in turn calls for physiological adjustments in O2 transfer systems; flux limits of the former must be matched by flux limits of the latter. Only then can an acceptably high scope for aerobic activity be achieved despite reduced O2 availability in inspired air. Such long-term match-up invariably calls for a left-shifted ODC plus other well known adjustments in O2 transport. In the short term, right shifting the ODC may increase the total amount of aerobic work possible (by favoring O2 unloading and thus raising tissue O2 concentration), yet maximum flux capacity cannot be changed much because mitochondrial metabolism is designed for maintaining stable rates of ATP synthesis even at widely varying O2 tensions. That is why even in short-term acclimatization, in order to increase flux capacity, the activities of oxidative enzymes also must be increased.

Acclimatization↗
PubMed1984

The design and the role of the nasal passages in temperature regulation in the dik-dik antelope (Rhynchotragus kirkii) with observations on the carotid rete.

Exhaled air temperatures (Tex) and rectal temperatures (Trec) were measured in five dik-dik antelopes under controlled environmental temperatures (Ta) between 15 and 40 degrees C. In addition morphometric analysis of the nasal passages, gross and histological identification of the carotid rete were carried out in an attempt to illustrate a possible brain cooling system in this small ungulate. Below Ta of 30 degrees C, Tex decreased with decreasing Ta leading to the establishment of a temperature gradient of about 20 degrees C between Ta and Trec at a Ta of around 15 degrees C. At Ta of 30 degrees C Tex was approximately half a degree lower than the Trec. Gross and histological studies revealed the presence of carotid rete and profuse vascularisation of the nasal turbinates. Morphometric analysis established a mean volume density of the nasal passages (np) in the splanchnocranium (sp) (VV(np,sp], surface density (SV(np,sp] and harmonic mean width of the nasal passages (W) of 9.5%, 2.15 cm2/cm3 and 1.23 mm, respectively. Combined physiological and anatomical measurements suggest that the dik-dik may possess an efficient brain cooling and water conserving system. The design of the upper respiratory system in these antelopes may help these animals to tolerate the extremes of temperatures and insolation encountered in their habitat.

Animals↗