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O Brix

Publications and source records attributed to O Brix.

28 records · Page 2Linked to original sources
PubMed1990

Lactate does facilitate oxygen unloading from the hemoglobin of the whale, Balaenoptera acutorostrata, after diving.

The present study reports on a specific effect of lactate on the oxygen binding properties of the hemoglobin from the whale, Balaenontera acutorostrata. In fact 0.1 mM lactate may increase the amount of oxygen unloaded to the tissues as much as 30%. Under these conditions the Bohr shift, of the magnitude of about -1, does not alter the oxygen affinity, but plays an important role in the isohydric transport of carbon dioxide.

Animals↗
PubMed1989

Arctic adaptation in reindeer. The energy saving of a hemoglobin.

Previous results [(1988) Arct. Med. Res. 47, 83-88] have shown that hemoglobin from reindeer is characterized by a low overall heat of oxygenation. This particular aspect has been investigated further in a series of precise oxygen equilibrium experiments. The results obtained show a peculiar dependence of the temperature effect on the fractional saturation of hemoglobin with oxygen, which could be regarded as a very interesting case of molecular adaptation to extreme environmental conditions.

2,3-Diphosphoglycerate↗
PubMed1989

Arctic life adaptation--I. The function of reindeer hemoglobin.

1. The functional properties of hemoglobin from the reindeer (Rangifer tarandus tarandus L.) are characterized as a function of pH, temperature and organic phosphate concentration. 2. Alongside overall similarities shared with most vertebrate hemoglobins, hemoglobin from the reindeer shows significant differences with respect to the effect of both organic phosphates and chloride anions. 3. The limited effect of temperature on oxygen binding (delta H = -4 kcal/mol O2) could be regarded as an interesting case of molecular adaptation to extreme environmental conditions.

Adaptation, Physiological↗
PubMed1989

Arctic life adaptation--II. The function of musk ox (Ovibos muschatos) hemoglobin.

1. The hemoglobin system from musk ox (Ovibos muschatos) has been characterized from the functional point of view with special regard to the effect of organic phosphates and temperature. 2. The results are similar to those previously obtained in the case of reindeer and confirm that hemoglobins from arctic animals may display very low enthalpy change for the reaction with oxygen. 3. This finding is considered an example of molecular adaptation of respiratory pigments to extreme environmental conditions.

Adaptation, Physiological↗
PubMed1989

Arctic life adaptation--III. The function of whale (Balaenoptera acutorostrata) hemoglobin.

1. The oxygen binding properties of the hemoglobin from the Lesser Rorqual, Balaenoptera acutorostrata, has been investigated with respect to the possible effects of organic phosphates on gas transport in arctic environments. 2. The intrinsic oxygen affinity of the hemoglobin is high and strongly modulated by the effects of organic phosphates. 3. In the absence of organic phosphates, the temperature sensitivity of oxygen binding expressed by the heat of oxygenation, delta H, is -16.2 kcal/mol when corrected for the heat of oxygen in solution. 4. In the presence of organic phosphates there is a marked decrease in the temperature sensitivity delta H approximately -5 kcal/mol). 5. This feature is of great importance for oxygen unloading in the flippers and the tail, where the temperature is lower than the trunk of the whale. 6. Furthermore the organic phosphates strongly increase the Bohr coefficient, delta log P50/delta pH, from less than -0.3 in stripped hemoglobin to about -1.5 when the hemoglobin is saturated with P6-inositol. 7. This feature may be of great physiological importance by reducing the CO2 tension and acidosis after a prolonged dive.

Adaptation, Physiological↗
PubMed1989

Hemoglobins from bats (Myotis myotis and Rousettus aegyptiacus): a possible example of molecular adaptation to different physiological requirements.

The functional properties of the hemoglobin systems from two different species of bat i.e. Rousettus aegyptiacus and Myotis myotis have been studied as a function of chloride, polyphosphates, pH and temperature. Apart from overall similarities shared with most mammalian hemoglobins, the two systems show significant differences with respect to the effect of chloride and temperature sensitivity. These findings have been related to the different physiological needs of the two species.

Animals↗
PubMed1984

Cardiac beat frequency and oxygen supply: a comparative study.

The length of diastole in mammals varies between approx 1 s (elephant) and 38 ms (shrew) which makes oxygen supply in high speed cardiac pumps in very small mammals precarious. High capillary density and high blood P50 are reported in mammals with high frequency cardiac cycle. Both are probably insufficient when cardiac frequency is exceedingly high (shrew: 1000 min-1). High respiratory efficiency due to large relative mitochondrial volume per cell (greater than 50%) seems to be preferential solution to maintain sufficient O2-gradient. Similar strategy, i.e. high relative cardiac mitochondrial volume was reported in analogous situation in ice-fish (Chaenocephalus aceratus) where O2 cardiac cell supply is difficult due to the absence of hemoglobin and cardiac myoglobin.

Animals↗
PubMed1981

The significance of the linkage between the Bohr and Haldane effects in cephalopod bloods.

This study concerns the physiological implications of the theoretical identity between the Bohr and Haldane effects in the hemocyanin containing blood from the cephalopods Loligo forbesii and Sepia officinalis. The Bohr factor is for both species lower than -1.0. The functional Haldane coefficient (delta ctCO2/delta cHcO2)pH ranges from -2.0 to -0.9 mMCO2/mMO2 in S. officinalis and from -1.2 to -0.7 mMCO2/mMO2 in L. forbesii. This implies for S. officinalis that there may not be enough protons produced from aerobic metabolism to facilitate the release of O2 from HcO2 via the pH sensitivity of this binding. The amount of anaerobically produced protons are predictably of little consequence for release of Hc bound O2 in cephalopods since octopine as the primary product of anaerobic metabolism is a much weaker acid than lactic acid at physiological pH. It is proposed that during burst swimming powered by the ventilatory current, such as practiced by many squids, the overall requirement for ventilation may increase causing a reduced pCO2 and bring the functional Haldane effect below unity. This implies that more H+ are produced by aerobic metabolism than can be found to hemocyanin, hence a shift of the O2 equilibrium curve to the right and improved O2 unloading potential. The advantage of the very large (pH sensitivity) Bohr shift in benthic forms like S. officinalis, both tolerant of and frequently experiencing hypoxic water, may rest with a marked increase in O2 affinity and improved O2 loading in response to respiratory alkalosis produced by hyperventilation.

Animals↗
PubMed1981

A modified Van Slyke apparatus.

A modified micro-Van Slyke apparatus for analyzing gases in a 25- to 100-microliter sample of blood or other solutions is described. The method is based on the vacuum-extraction principle in which the gases are released for direct manometric measurement. A determination of total CO2 and total O2 content in blood can be completed in about 7 in. A commercial micro-Van Slyke apparatus (Thomas Magna-Matic manometer apparatus) requires 10-15 min for the same determination. The modified Van Slyke can be operated under field conditions without losing accuracy. The modified Van Slyke apparatus has greater reproducibility and accuracy than the commercial model.

Acid-Base Equilibrium↗