Body temperature and oxygen consumption of two malaysian prosimians

The body temperature and oxygen consumption of freshly trapped Slow Loris (Nycticebus coucang) and Common Tree Shrews (Tupaia glis) were measured in Malaysia. The Slow Loris had a low body temperature and oxygen consumption, while the values for the Common Tree Shrew were relatively high. The data are discussed in relation to information obtained from captive animals. The importance of the Slow Loris is stressed because it represents one of the few natural hypometabolic states in primates.     

Postprandial gastrointestinal blood flow, oxygen consumption and heart rate in rainbow trout (Oncorhynchus mykiss)

The present study is the first to simultaneously and continuously measure oxygen consumption (MO₂) and gastrointestinal blood flow (q_gi) in fish. In addition, while it is the first to compare the effects of three isoenergetic diets on q_gi in fish, no significant differences among diets were found for postprandial MO₂, q_gi or heart rate (f_H) in rainbow trout, Oncorhynchus mykiss. Postprandial q_gi, f_H and MO₂ were significantly elevated above baseline levels by 4 h. Postprandial q_gi peaked at 136% above baseline after 11 h, f_H peaked at 110% above baseline after 14 h and MO₂ peaked at 96% above baseline after 27 h. Moreover, postprandial MO₂ remained significantly elevated above baseline longer than q_gi (for 41 h and 30 h, respectively), perhaps because most of the increase in MO₂ associated with feeding is due to protein handling, a process that continues following the absorption of nutrients which is thought to be the primary reason for the elevation of q_gi. In addition to the positive relationships found between postprandial MO₂ and q_gi and between postprandial MO₂ and f_H, we discovered a novel relationship between postprandial q_gi and f_H.     

Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammals

We questioned whether the amplitudes of the circadian pattern of body temperature (T(b)), oxygen consumption (V (O(2))) and heart rate (HR) changed systematically among species of different body weight (W). Because bodies of large mass have a greater heat capacitance than those of smaller mass, if the relative amplitude (i.e., amplitude/mean value) of metabolic rate was constant, one would expect the T(b) oscillation to decrease with the increase in the species W. We compiled data of T(b), V (O(2)) and HR from a literature survey of over 200 studies that investigated the circadian pattern of these parameters. Monotremata, Marsupials and Chiroptera, were excluded because of their characteristically low metabolic rate and T(b). The peak-trough ratios of V (O(2)) (42 species) and HR (35 species) averaged, respectively, 1.57+/-0.08, and 1.35+/-0.07, and were independent of W. The daily high values of T(b) did not change, while the daily low T(b) values slightly increased, with the species W; hence, the high-low T(b) difference (57 species) decreased with W (3.3 degrees C.W(-0.13)). However, the decrease in T(b) amplitude with W was much less than expected from physical principles, and the high-low T(b) ratio remained significantly above unity even in the largest mammals. Thus, it appears that in mammals, despite the huge differences in physical characteristics, the amplitude of the circadian pattern is a fixed (for V (O(2)) and HR), or almost fixed (for T(b)), fraction of the 24-h mean value. Presumably, the amplitudes of the oscillations are controlled parameters of physiological significance.     

Predicting rate of oxygen consumption from heart rate while little penguins work, rest and play.

The relationship between heart rate (f(H)) and rate of oxygen consumption (V(.)O2) was investigated under changing conditions of ambient temperature, digestive state and exercise state in the little penguin (Eudyptula minor). Both f(H) and V(.)O2 were recorded simultaneously from 12 little penguins while they each (a) rested and exercised within their reported thermo-neutral zone (TNZ), (b) rested and exercised below their reported TNZ and (c) digested a meal of sardines within their reported TNZ. Contrary to our expectations, we found that minimum V(.)O2 did not vary between the two temperatures used. Comparison with values from the literature suggests that both minimum V(.)O2 and the extent of the TNZ in this species may vary along a latitudinal gradient. Furthermore, while minimum V(.)O2 was unchanged at the lower temperature, minimum f(H) was significantly higher, suggesting a hitherto undescribed cardiac response to lowered ambient temperature in an avian species. This response was maintained when the penguins exercised within and below their apparent TNZ as f(H) was significantly greater in cold conditions for a given level of V(.)O2. Furthermore, both f(H) and V(.)O2 were slightly but significantly elevated for a given walking speed during exercise at the lower temperature. This suggests that the penguins may have been close to their TNZ and that the measures employed to counteract heat loss while at rest may have been compromised during exercise. There was no significant difference in the relationship between f(H) and V(.)O2 while the penguins were inactive ina post-digestive state or inactive and digesting a meal within their TNZ, though both of these relationships were significantly different from that during exercise. This suggests that while digestion has no effect on the f(H)/V(.)O2 relationship, for little penguins at least, it is of little value in deriving a predictive relationship for application to active free-ranging animals.     

Grey flesh fly (Wohlfahrtia vigil) parasitism of a Preble's meadow jumping mouse (Zapus hudsonius preblei)

A Preble's meadow jumping mouse (Zapus hudsonius preblei) parasitized by five grey flesh fly (Wohlfahrtia vigil) larvae was discovered at the United States Air Force Academy in Colorado Springs, Colorado (USA), in June 1998. This is the first documented case of grey flesh fly parasitism of jumping mice (Family Dipodidae). The lesion was approximately 6 mm wide and was partially hidden under a mat of wet fur. Myiasis was found in one (0.7%) of 146 jumping mice captured at the Academy in 1998. The Preble's meadow jumping mouse is considered a threatened subspecies by the United States Fish and Wildlife Service. Although grey flesh fly myiasis can be fatal, it is unknown whether it is affecting populations of Preble's meadow jumping mouse. This is the first report of grey flesh fly myiasis in free-ranging wildlife in Colorado.     

The relationship between rate of oxygen consumption, heart rate and thermal conductance of the dik-dik antelope (Rhynchotragus kirkii) at various ambient temperatures

1. The extent of cardiovascular adjustments to heat and cold were investigated between ambient temperatures of 5 and 45 degrees C by measuring conductance and the rates of oxygen consumption and heart beats. 2. Minimum heart rate was observed at 25 degrees C (114 +/- 9 beats/min). In the heat at 45 degrees C heart rate was observed to increase only slightly (127 +/- 12 beats/min) but in the cold -5 degrees C heart rate nearly doubled that at 25 degrees C. 3. Thermal conductance was on average 0.031 mlO2 (g. hr. degrees C)-1 below 25 degrees C but increased by more than 20 times at 40 degrees C. 4. A positive correlation between heart rate and rate of oxygen consumption was demonstrated below 25 degrees C and the relation may be of practical use.     

The effect of activity on oxygen consumption,oxygen debt,and heart rate in the lizardsVaranus gouldii andsauromalus hispidus

Summary Oxygen consumption and heart rate were measured during rest and activity in the lizardsVaranus gouldii andSauromalus hispidus. Oxygen debt was calculated from postactive oxygen consumption. Standard metabolic rates of the two animals are similar butVaranus consumes much more oxygen during activity than doesSauromalus (Fig. 1–3). The latter has a constant active metabolic rate above 30 ° C and accumulates a large oxygen debt, which is repayed slowly (Fig. 4).Varanus recovers rapidly from activity (Fig. 5), presumably because of the smaller lactacid debt incurred. Heart rate increment inSauromalus is high (Fig. 8). This variable cannot be responsible for the limitation of active oxygen consumption; calculations of oxygen pulse suggest that an inability to increase A-V difference and/or stroke volume are implicated (Fig. 9).Varanus have evolved mechanisms to sustain high levels of oxygen consumption superior to those of other reptiles investigated. The role of anaerobiosis in the biology of both animals is discussed.     

Estimating the rate of oxygen consumption during submersion from the heart rate of diving animals

How animals manage their oxygen stores during diving and other breath-hold activities has been a topic of debate among physiologists for decades. Specifically, while the behavior of free-ranging diving animals suggests that metabolism during submersion must be primarily aerobic in nature, no studies have been able to determine their rate of oxygen consumption during submersion (Vo(2)d) and hence prove that this is the case. In the present study, we combine two previously used techniques and develop a new model to estimate Vo(2)d accurately and plausibly in a free-ranging animal and apply it to data for macaroni penguins (Eudyptes chrysolophus) as an example. For macaroni penguins at least, Vo(2)d can be predicted by measuring heart rate during the dive cycle and the subsequent surface interval duration. Including maximum depth of the dive improves the accuracy of these predictions. This suggests that energetically demanding locomotion events within the dive combine with the differing buoyancy and locomotion costs associated with traveling to depth to influence its cost in terms of oxygen use. This will in turn effect the duration of the dive and the duration of the subsequent recovery period. In the present study, Vo(2)d ranged from 4 to 28 ml.min(-1).kg(-1), indicating that, at least as far as aerobic metabolism was concerned, macaroni penguins were often hypometabolic, with rates of oxygen consumption usually below that for this species resting in water (25.6 ml.min(-1).kg(-1)) and occasionally lower than that while resting in air (10.3 ml.min(-1).kg(-1)).     

The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).