Capillary density in mammals in relation to body size and oxygen consumption

The high metabolic rate per gram of tissue in small mammals requires that oxygen be supplied to the tissues at a higher rate than in larger animals. The high rate of oxygen delivery in the small animal can be accomplished by a) higher capillary density and b) higher unloading tension for oxygen. Both these factors in the oxygen supply vary with body size in such a manner that delivery of oxygen to the tissues is facilitated in the small animal. This paper gives comparative data on capillary density in muscles from 10 mammals of various size. The smallest mammals have significantly higher capillary densities, but the trend is not evident throughout the size range examined. It is therefore reasonable to assume that the factors that relate capillary density and body size are overshadowed by variables such as activity, domestication, cold acclimation, etc., and, perhaps primarily, the size of the muscle fibers, which (although dependent on body size) varies considerably with the type of muscle and its use.

Download Full-text

Intestinal and Cerebral Oxygenation during Severe Isovolemic Hemodilution and Subsequent Hyperoxic Ventilation in a Pig Model

Anesthesiology ◽

10.1097/00000542-200209000-00021 ◽

2002 ◽

Vol 97 (3) ◽

pp. 660-670 ◽

Cited By ~ 80

Author(s):

Jasper van Bommel ◽

Adrianus Trouwborst ◽

Lothar Schwarte ◽

Martin Siegemund ◽

Can Ince ◽

...

Keyword(s):

Oxygen Consumption ◽

Oxygen Delivery ◽

Oxygen Supply ◽

Cerebral Oxygenation ◽

Oxygen Extraction ◽

Control Group ◽

Isovolemic Hemodilution ◽

Systemic Oxygen ◽

Fraction Of Inspired Oxygen ◽

Hyperoxic Ventilation

Background During severe isovolemic hemodilution, determination of critical hematocrit levels for the microvascular oxygenation of different organs might provide more insight into the effect of the redistribution of blood flow and oxygen delivery on the oxygenation of different organs. The effect of an increased amount of dissolved oxygen on tissue oxygenation during severely decreased hematocrit levels is not clear. Methods Fifteen anesthetized pigs were randomized between an experimental group (n = 10), in which severe isovolemic hemodilution was performed with 6% hydroxyethylstarch (1:1), and a time-matched control group (n = 5). Systemic, intestinal, and cerebral hemodynamic and oxygenation parameters were monitored. Microvascular oxygen partial pressure (muPo(2) ) was measured in the cerebral cortex and the intestinal serosa and mucosa, using the oxygen-dependent quenching of Pd-porphyrin phosphorescence. In the final phase of the experiment, fraction of inspired oxygen was increased to 1.0. Results Hemodilution decreased hematocrit from 25.3 +/- 3.0 to 7.6 +/- 1.2% (mean +/- SD). Systemic and intestinal oxygen delivery fell with the onset of hemodilution; intestinal oxygen consumption deceased at a hematocrit of 9.9%, whereas the systemic oxygen consumption decreased at a hematocrit of 7.6%. During hemodilution, the intestinal and cerebral oxygen extraction ratios increased from baseline with 130 and 52%, respectively. Based on the intersection of the two best-fit regression lines, determined by a least sum of squares technique, similar critical hematocrit levels were found for systemic oxygen consumption and the cerebral and intestinal mucosa muPo(2); the intestinal serosa muPo(2) decreased at an earlier stage (P < 0.05). Hyperoxic ventilation improved the muPo(2) values but not systemic or intestinal oxygen consumption. Conclusions During isovolemic hemodilution, the diminished oxygen supply was redistributed in favor of organs with a lower capacity to increase oxygen extraction. It is hypothesized that redirection of the oxygen supply within the intestines resulted in the preservation of oxygen consumption and mucosal muPo(2) compared with serosal muPo(2).

Download Full-text

Oxygen Dissociation Curves of Mammalian Blood in Relation To Body Size

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1958.195.2.424 ◽

1958 ◽

Vol 195 (2) ◽

pp. 424-428 ◽

Cited By ~ 158

Author(s):

Knut Schmidt-Neilsen ◽

James L. Larimer

Keyword(s):

Body Size ◽

Small Animal ◽

Capillary Density ◽

Dissociation Curve ◽

Oxygen Dissociation ◽

Mammalian Blood ◽

Tissue Cells ◽

Dissociation Curves

Oxygen dissociation curves were determined in mammalian blood at the CO2 tension of the organism, without the addition of buffers, dilution of the blood, or other alterations. It appears that the dissociation curve is related to body size in such a way that the blood of smaller animals has a higher unloading tension for oxygen. This finding is discussed in relation to the higher metabolic need for oxygen of the smaller animal. It is suggested that, in addition to the higher capillary density in the small animal, a higher unloading tension for oxygen also contributes to the steepness of the diffusion gradient for oxygen from the capillary to the tissue cells.

Download Full-text

Body Size in Relation to Oxygen Consumption and Pleopod Beat in Ligia Oceanica L

Journal of Experimental Biology ◽

10.1242/jeb.28.4.492 ◽

1951 ◽

Vol 28 (4) ◽

pp. 492-507 ◽

Cited By ~ 1

Author(s):

C. ELLENBY

Keyword(s):

Body Weight ◽

Oxygen Consumption ◽

Body Size ◽

Body Length ◽

Body Shape ◽

Size Range ◽

Total Oxygen ◽

Rate Of Oxygen Consumption ◽

Relationship Of ◽

The Relationship

1. Male Ligia oceanica were used in an investigation of the relationship of body size to rate of oxygen consumption and pleopod beat. 2. Animals varied in weight from 0.04 to 1.03 g. and from 0.95 to 3.1 cm. in length. 3. Body shape does not change significantly over the size range, for length and breadth both increase at the same rate, and pleopod dimensions bear a constant relation to body length. 4. Specific gravity also is constant, for the relation of body weight to the cube of body length shows no trend with increasing size. 5. Oxygen consumption per gram decreases with increasing size and is proportional to the -0.274 Power of body weight. Total oxygen consumption is therefore proportional to the 0.726 power of body weight; but this value does not differ significantly from two-thirds. 6. As shape is constant, surface area is proportional to the square of a linear dimension. It is shown that oxygen consumption per unit of length2 is constant over the size range. Although body length was measured far less accurately than body weight it is shown that it assesses ‘body size’ more accurately. 7. Rate of pleopod beat was measured at 15 and 25°C.; it decreases with the size of the animal. At 15°C. time per beat varies as the 0.66 power of body length, and at 25°C. as the 0.59 power; neither of these values differs significantly from 0.5. Despite the fact that pleopod movement is heavily damped, the rate therefore varies like that of a pendulum. 9. The workof Fox (1936-9) and Fox et al. (1937a)on the rate of oxygen consumption of animals from cold and warmer seas and from different habitats is considered. It is suggested that many of their comparisons are invalidated by differences in body size of the animals concerned, and that, in relation to environment, no basis, theoretical or experimental, has been established for a distinction between ‘nonlocomotory’ and ‘activity’ metabolism.

Download Full-text

The Respiration of Freshwater Snails

Journal of Experimental Biology ◽

10.1242/jeb.36.4.690 ◽

1959 ◽

Vol 36 (4) ◽

pp. 690-708

Author(s):

KAJ BERG ◽

K. W. OCKELMANN

Keyword(s):

Oxygen Consumption ◽

Body Size ◽

Oxygen Content ◽

Oxygen Supply ◽

Regression Line ◽

Live Weight ◽

Interspecific Variation ◽

Freshwater Snails ◽

Low Oxygen ◽

Bithynia Tentaculata

1. The oxygen consumption of some Danish freshwater snails was studied in relation to varying periods of starvation, varying temperatures, weight of animals and oxygen content of the water. The observed respiration is a moderately active metabolism, not a basal one. 2. In the case of Lymnaea palustris and Bithynia leachi a distinct decrease of oxygen consumption has been found in the period 1-24 hr. after collecting; the decrease is supposed to be caused by starvation. In similar experiments Lymnaea pereger, Myxas giutinosa, Bithynia tentaculata, Valvata piscinalis and possibly Physafontinalis and Lymnaea auricularia show only a small decrease (or no decrease) of oxygen consumption. 3. During a gradual increase of the temperature (c. I° C. per hr.) the snails increase their oxygen consumption by 65-90% of the increase expected from Krogh's curve. In the case of Myxas glutinosa and Physa fontinalis the increase of respiration was nearly the same as that found by Krogh for other animals. 4. The relation of oxygen consumption to body size (live weight) is not a fixed, unchangeable quantity characteristic of every species, but may vary seasonally. A tentative explanation of this variation is given. 5. The oxygen consumption in relation to body size has also an interspecific variation. In prosobranchs the slopes b of the regression lines in a logarithmic co-ordinate system have in some cases nearly the magnitude 0.67 required by the surface law, but others are higher, e.g. c. 0.95. In pulmonates the relation varies as much as from b=c. 0.45 to b=c. 1.00, i.e. between less than proportional to surface and proportional to weight. 6. The oxygen consumption of the freshwater snails in relation to the sizes of the standard individuals is depicted in a logarithmic co-ordinate system as a belt showing only a slight deviation (Fig. 4, p. 697), i.e. the snails regarded as a whole have a fairly uniform respiration. The regression line of oxygen consumption to sizes of the standard individuals seems to be expressed by a regression line with a slope just under 1.0. 7. Experiments on oxygen consumption in relation to oxygen content of the water have shown that some species (Lymnaea auricularia, Myxas glutinosa, Physafontinalis, Valvata piscinalis and Bithynia leachi) are able to maintain their consumption with decreasing oxygen content of the water to a critical point of oxygen supply. But in some other species (Lymnaea pereger, L. palustris and Bithynia tentaculata) oxygen consumption decreases immediately in response to a declining oxygen supply. 8. In some freshwater snails (Myxas glutinosa, Lymnaea pereger, Physa fontinalis) the decrease in oxygen consumption in response to a decreasing oxygen supply is not gradual, but shows a steep fall below certain low values of the oxygen content. The only species able to maintain a comparatively high oxygen consumption at low oxygen supply is Bithynia leachi.

Download Full-text

Delaying Blood Transfusion in Experimental Acute Anemia with a Perfluorocarbon Emulsion

Anesthesiology ◽

10.1097/aln.0b013e31820efb36 ◽

2011 ◽

Vol 114 (4) ◽

pp. 901-911 ◽

Cited By ~ 11

Author(s):

Pedro Cabrales ◽

Juan Carlos Briceño

Keyword(s):

Oxygen Consumption ◽

Oxygen Delivery ◽

Tissue Oxygenation ◽

Oxygen Carrier ◽

Capillary Density ◽

Functional Capillary Density ◽

Peripheral Tissue ◽

Control Group ◽

Oxygen Extraction Ratio ◽

Perfluorocarbon Emulsion

Background To avoid unnecessary blood transfusions, physiologic transfusion triggers, rather than exclusively hemoglobin-based transfusion triggers, have been suggested. The objective of this study was to determine systemic and microvascular effects of using a perfluorocarbon-based oxygen carrier (PFCOC) to maintain perfusion and oxygenation during extreme anemia. Methods The hamster (weight, 55-65 g) window chamber model was used. Two isovolemic hemodilution steps were performed using hydroxyethyl starch, 10%, at normoxic conditions to a hematocrit of 19% (hemoglobin, 5.5 g/dl), the point at which the transfusion trigger was reached. Two additional hemodilution exchanges using the PFCOC (Oxycyte) and increasing the fraction of inspired oxygen to 1.0 were performed to reduce the hematocrit to 11% (hemoglobin, 3.8 g/dl) and 6% (hemoglobin, 2.0 g/dl), respectively. No control group was used in the study because this concentration of hemodilution is lethal with conventional plasma expanders. Systemic parameters, microvascular perfusion, functional capillary density, and oxygen tensions across the microvascular network were measured. Results At 6% hematocrit, the PFCOC maintained mean arterial pressure, cardiac output, systemic oxygen delivery, and oxygen consumption. As hematocrit was decreased from 11% to 6%, functional capillary density, calculated microvascular oxygen delivery, and oxygen consumption decreased; and the oxygen extraction ratio was close to 100%. Peripheral tissue oxygenation was not predicted by systemic oxygenation. Conclusions The PFCOC, in conjunction with hyperoxia, was able to sustain organ function and partially provide systemic oxygenation during extreme anemia during the observation period. The PFCOC can work as a bridge until erythrocytes are available for transfusion or when additional oxygen is required, despite the possible limitations in peripheral tissue oxygenation.

Download Full-text

The combined effect of body size and temperature on oxygen consumption rates and the size‐dependency of preferred temperature in European perch Perca fluviatilis

Journal of Fish Biology ◽

10.1111/jfb.14807 ◽

2021 ◽

Vol 98 (6) ◽

pp. 1556-1556

Keyword(s):

Oxygen Consumption ◽

Body Size ◽

Perca Fluviatilis ◽

Combined Effect ◽

European Perch ◽

Preferred Temperature ◽

Size Dependency ◽

Perch Perca Fluviatilis ◽

Consumption Rates

Download Full-text

alpha-Adrenergic control of oxygen delivery to myocardium during exercise in conscious dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1982.242.5.h805 ◽

1982 ◽

Vol 242 (5) ◽

pp. H805-H809 ◽

Cited By ~ 17

Author(s):

G. R. Heyndrickx ◽

P. Muylaert ◽

J. L. Pannier

Keyword(s):

Heart Rate ◽

Blood Flow ◽

Oxygen Consumption ◽

Coronary Blood Flow ◽

Coronary Sinus ◽

Oxygen Delivery ◽

Left Ventricular ◽

Conscious Dogs ◽

Adrenergic Blockade ◽

Adrenergic Control

alpha-Adrenergic control of the oxygen delivery to the myocardium during exercise was investigated in eight conscious dogs instrumented for chronic measurements of coronary blood flow, left ventricular (LV) pressure, aortic blood pressure, and heart rate and sampling of arterial and coronary sinus blood. After alpha-adrenergic receptor blockade a standard exercise load elicited a significantly greater increase in heart rate, rate of change of LV pressure (LV dP/dt), LV dP/dt/P, and coronary blood flow than was elicited in the unblocked state. In contrast to the response pattern during control exercise, there was no significant change in coronary sinus oxygen tension (PO2), myocardial arteriovenous oxygen difference, and myocardial oxygen delivery-to-oxygen consumption ratio. It is concluded that the normal relationship between myocardial oxygen supply and oxygen demand is modified during exercise after alpha-adrenergic blockade, whereby oxygen delivery is better matched to oxygen consumption. These results indicate that the increase in coronary blood flow and oxygen delivery to the myocardium during normal exercise is limited by alpha-adrenergic vasoconstriction.

Download Full-text

Oxygen Supply Method Using Gas-Permeable Film for Wastewater Treatment

Water Science & Technology ◽

10.2166/wst.1993.0169 ◽

1993 ◽

Vol 28 (7) ◽

pp. 243-250 ◽

Cited By ~ 17

Author(s):

Y. Suzuki ◽

S. Miyahara ◽

K. Takeishi

Keyword(s):

Wastewater Treatment ◽

Energy Consumption ◽

Oxygen Transfer ◽

Transfer Rate ◽

Oxygen Supply ◽

Oxygen Transfer Rate ◽

High Energy ◽

High Rate ◽

N Removal ◽

High Energy Consumption

Gas-permeable film can separate air and water, and at the same time, let oxygen diffuse from the air to the water through the film. An oxygen supply method using this film was investigated for the purpose of reducing energy consumption for wastewater treatment. The oxygen transfer rate was measured for the cases with or without biofilm, which proved the high rate of oxygen transfer in the case with nitrifying biofilm which performed nitrification. When the Gas-permeable film with nitrifying biofilm was applied to the treatment of wastewater, denitrifying biofilm formed on the nitrifying biofilm, and simultaneous nitrification and denitrification occurred, resulting in the high rate of organic matter and T-N removal (7 gTOC/m2/d and 4 gT-N/m2/d, respectively). However, periodic sloughing of the denitrifying biofilm was needed to keep the oxygen transfer rate high. Energy consumption of the process using the film in the form of tubes was estimated to be less than 40% of that of the activated sludge process.

Download Full-text