Potential impact of metabolic acidosis on the fixed-acid Bohr effect in snapper (Pagrus auratus) following angling stress

The oxygen dissociation curve and Bohr effect were measured in normal whole blood as a function of carboxyhemoglobin concentration [HbCO]. pH was changed by varying CO2 concentration (CO2 Bohr effect) or by addition of isotonic NaOH or HCl at constant PCO2 (fixed acid Bohr effect). As [HbCO] varied through the range of 2, 25, 50, and 75%, P50 was 26.3, 18.0, 11.6, and 6.5 mmHg, respectively. CO2 Bohr effect was highest at low oxygen saturations. This effect did not change as [HbCO] was increased. However, as [HbCO] was increased from 2 to 75%, the fixed acid Bohr factor increased in magnitude from -0.20 to -0.80 at very low oxygen saturations. The effect of molecular CO2 binding (carbamino) on oxygen affinity was eliminated at high [HbCO]. These results are consistent with the initial binding of O2 or CO to thealpha-chain of hemoglobin. The results also suggest that heme-heme interaction is different for oxygen than for carbon monoxide.

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Bohr effect induced by CO2 and fixed acid at various levels of O2 saturation in duck blood

Pflügers Archiv - European Journal of Physiology ◽

10.1007/bf00584956 ◽

1978 ◽

Vol 376 (3) ◽

pp. 237-240 ◽

Cited By ~ 17

Author(s):

M. Meyer ◽

J. P. Holle ◽

P. Scheid

Keyword(s):

Bohr Effect ◽

Fixed Acid

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Effect of metabolic acidosis on pulmonary gas exchange of artificially ventilated dogs

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.5.2301 ◽

1993 ◽

Vol 74 (5) ◽

pp. 2301-2308 ◽

Cited By ~ 10

Author(s):

A. Frans ◽

T. Clerbaux ◽

E. Willems ◽

F. Kreuzer

Keyword(s):

Metabolic Acidosis ◽

Dynamic Method ◽

Bohr Effect ◽

Arterial Pco2 ◽

Before And After ◽

Two Factors ◽

Simultaneous Decrease ◽

Pulmonary Arterial ◽

Co2 Excretion ◽

Oxyhemoglobin Dissociation

It is well established that metabolic acidosis induces a reduction in alveolar-arterial O2 difference [(A-a)Do2] in artificially ventilated dogs by shifting the oxyhemoglobin dissociation curve (ODC) and/or by improving the distribution of the ventilation-to-perfusion ratio (VA/Q) throughout the lung. To assess the influence of these two factors we examined eight artificially ventilated dogs before and after induction of metabolic acidosis by a perfusion of 0.3 mol HCl. We measured classic indexes of cardiopulmonary function. VA/Q distribution was estimated using the multiple inert gas elimination technique (MIGET). ODC and Bohr effect of each dog were obtained by a dynamic method. Acidosis increased CO2 excretion, respiratory quotient, blood PO2 at 50% saturation, and arterial PCO2 and PO2 with a simultaneous decrease in (A-a)DO2. In seven dogs, the distribution of VA and Q, as assessed by MIGET, was not substantially modified by HCl perfusion. In the eighth dog the distribution of Q and VA became more homogeneous after acidosis. This led us to conclude that the Bohr effect is the most important and most consistently observed factor responsible for the decrease in (A-a)DO2 found in metabolic acidosis. In rare cases the increase in pulmonary arterial pressure may complement this action by improving the distribution of the VA/Q ratio.

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Saturation dependency of the Bohr effect: interactions among H-+, CO2, and DPG

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.6.1126 ◽

1975 ◽

Vol 38 (6) ◽

pp. 1126-1131 ◽

Cited By ~ 45

Author(s):

M. P. Hlastala ◽

R. D. Woodson

Keyword(s):

Oxygen Saturation ◽

Base Excess ◽

Oxygen Affinity ◽

Co2 Concentration ◽

Bohr Effect ◽

Blood Oxygen Saturation ◽

Relative Contribution ◽

Lower Oxygen ◽

Lower Saturation ◽

Fixed Acid

The Bohr effect was measured in normal whole blood and in blood with low DPG concentration as a function of oxygen saturation. pH was changed by varying CO2 concentration (CO2 Bohr effect) or by addition of isotonic NaOH or HC1 at constant PCO2 (fixed acid Bohr effect). At nornal DPG concentration CO2 Bohr effect was -0.52 at 50% blood oxygen saturation, increasing in magnitude at lower saturation and decreasing in magnitude at higher saturation. In DPG depleted blood with base excess (BE) similar to 0 meq/1, there was similar dependence of CO2 Bohr effect on oxygen saturation. At BE similar to -10 meq/1, influence of saturation was comparable, but the magnitude of the Bohr effect was markedly increased at all saturations. Fixed acid Bohr effect at normal DPG concentration was -0.45 at saturations of 50–90% but decreased at lower saturations. In DPG-depleted blood fixed acid Bohr effect averaged about -0.33 with minimal variation with saturation. Influence of DPG on oxygen affinity was greater at intermediate saturations and less at saturations below 20% and above 80%. Effect of CO2, independent of pH, was many fold greater at lower oxygen saturations than at higher saturations. These results support the suggestion that the alpha chain of hemoglobin is the site of the initial oxygenation reaction. Physiologically they indicate that the relative contribution of CO2 and fixed acid, as well as the level of oxygen saturation and DPG concentration, may be important in determining PO2 of capillary blood and resulting oxygen delivery.

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HOMEOSTATIC ADJUSTMENTS AFTER EXERCISE

The Journal of General Physiology ◽

10.1085/jgp.27.3.143 ◽

1944 ◽

Vol 27 (3) ◽

pp. 143-154

Author(s):

Nathan W. Shock

Keyword(s):

Metabolic Acidosis ◽

Ammonium Chloride ◽

Normal Values ◽

Adult Males ◽

Acid Base ◽

Maximum Displacement ◽

Base Equilibrium ◽

Acid Base Equilibrium ◽

Severe Exercise ◽

Fixed Acid

The rate at which displacement and recovery of the acid-base equilibrium of the blood occur in young adult males subjected to short periods of maximal exertion has been determined. Displacement of acid-base equilibrium produced by severe exercise is along the fixed acid path, similar to the path of displacement produced by ingestion of acidifying agents such as ammonium chloride. Maximum displacement of the acid-base equilibrium is not reached until 7 to 10 minutes after the cessation of exercise. By this time over 50 per cent of the displacement in oxygen consumption, respiratory volume, and blood pressure have disappeared. A much greater metabolic acidosis was produced by exercise than could be induced by the oral administration of ammonium chloride. Recovery from the metabolic acidosis produced by exercise was much more rapid (10 times) than was recovery from the acidosis produced by ammonium chloride. After exercise the pH, returned to normal values more rapidly than did the bicarbonate content of the serum.

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Effects of Gender, Parental Role, and Time on Infant- and Adult-Directed Read and Spontaneous Speech

Journal of Speech Language and Hearing Research ◽

10.1044/2019_jslhr-s-19-0047 ◽

2019 ◽

Vol 62 (11) ◽

pp. 4001-4014

Author(s):

Melanie Weirich ◽

Adrian Simpson

Keyword(s):

Parental Involvement ◽

Gender Identity ◽

Spontaneous Speech ◽

First Year ◽

Space Size ◽

Vowel Space ◽

Potential Impact ◽

Phonetic Features ◽

And Gender ◽

Description Task

Purpose The study sets out to investigate inter- and intraspeaker variation in German infant-directed speech (IDS) and considers the potential impact that the factors gender, parental involvement, and speech material (read vs. spontaneous speech) may have. In addition, we analyze data from 3 time points prior to and after the birth of the child to examine potential changes in the features of IDS and, particularly also, of adult-directed speech (ADS). Here, the gender identity of a speaker is considered as an additional factor. Method IDS and ADS data from 34 participants (15 mothers, 19 fathers) is gathered by means of a reading and a picture description task. For IDS, 2 recordings were made when the baby was approximately 6 and 9 months old, respectively. For ADS, an additional recording was made before the baby was born. Phonetic analyses comprise mean fundamental frequency (f0), variation in f0, the 1st 2 formants measured in /i: ɛ a u:/, and the vowel space size. Moreover, social and behavioral data were gathered regarding parental involvement and gender identity. Results German IDS is characterized by an increase in mean f0, a larger variation in f0, vowel- and formant-specific differences, and a larger acoustic vowel space. No effect of gender or parental involvement was found. Also, the phonetic features of IDS were found in both spontaneous and read speech. Regarding ADS, changes in vowel space size in some of the fathers and in mean f0 in mothers were found. Conclusion Phonetic features of German IDS are robust with respect to the factors gender, parental involvement, speech material (read vs. spontaneous speech), and time. Some phonetic features of ADS changed within the child's first year depending on gender and parental involvement/gender identity. Thus, further research on IDS needs to address also potential changes in ADS.

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Exploring the Potential Impact of Sentence-Level Comprehension and Sentence-Level Fluency on Deaf Students' Passage Comprehension

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-19-00205 ◽

2020 ◽

Vol 63 (7) ◽

pp. 2281-2292

Author(s):

Ying Zhao ◽

Xinchun Wu ◽

Hongjun Chen ◽

Peng Sun ◽

Ruibo Xie ◽

...

Keyword(s):

Independent Predictor ◽

Vocabulary Knowledge ◽

Group Differences ◽

Regression Analyses ◽

Deaf Students ◽

Mediating Role ◽

Sentence Level ◽

Mediating Mechanisms ◽

Potential Impact ◽

The Relationship

Purpose This exploratory study aimed to investigate the potential impact of sentence-level comprehension and sentence-level fluency on passage comprehension of deaf students in elementary school. Method A total of 159 deaf students, 65 students ( M age = 13.46 years) in Grades 3 and 4 and 94 students ( M age = 14.95 years) in Grades 5 and 6, were assessed for nonverbal intelligence, vocabulary knowledge, sentence-level comprehension, sentence-level fluency, and passage comprehension. Group differences were examined using t tests, whereas the predictive and mediating mechanisms were examined using regression modeling. Results The regression analyses showed that the effect of sentence-level comprehension on passage comprehension was not significant, whereas sentence-level fluency was an independent predictor in Grades 3–4. Sentence-level comprehension and fluency contributed significant variance to passage comprehension in Grades 5–6. Sentence-level fluency fully mediated the influence of sentence-level comprehension on passage comprehension in Grades 3–4, playing a partial mediating role in Grades 5–6. Conclusions The relative contributions of sentence-level comprehension and fluency to deaf students' passage comprehension varied, and sentence-level fluency mediated the relationship between sentence-level comprehension and passage comprehension.

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