Acid-Base Balance: Origin of Plasma [H+] During Exercise

1995 ◽  
Vol 20 (3) ◽  
pp. 341-356 ◽  
Author(s):  
John M. Kowalchuk ◽  
Barry W. Scheuermann
Keyword(s):  
Strong Ion Difference ◽  
Weak Acids ◽  
Acid Base Balance ◽  
Acid Base ◽  
Independent Variables ◽  
Electrical Neutrality ◽  
Dissociation Equilibrium ◽  
Dependent Variables ◽  
Base Balance ◽  
Physicochemical Approach

According to physicochemical principles, the plasma concentration of hydrogen ions ([H+]), bicarbonate ([HCO3−]), and other acid-base-dependent variables are determined by the plasma PCO2; the strong ion difference ([SID+] = Σ[strong cations] − Σ[strong anions]); and the concentration of weak acids ([ATOT] = [HA] + [A−]). The physicochemical interactions between the acid-base-independent and dependent variables must recognize the constraints imposed by the law of electrical neutrality, dissociation equilibrium of weak acids and water, and the conservation of mass. This review demonstrates the usefulness of the physicochemical approach in studying plasma acid-base control during progressive exercise to exhaustion where the work rate was increased as either a slow (8 W/min) or fast (65 W/min) ramp function. The factors contributing to changes in the concentration of the acid-base-independent variables, and the contribution of the acid-base-independent variables to the plasma [H+] and [HCO3−] during exercise, will be discussed. Key words: PCO2, strong ion difference, weak acids, lactate, potassium

Extreme Derangements of Acid-Base Balance in Exercise: Advantages and Limitations of the Stewart Analysis

1995 ◽  
Vol 20 (3) ◽  
pp. 369-379 ◽  
Author(s):  
M. Roger Fedde ◽  
Richard L. Pieschl Jr.
Keyword(s):  
Dissociation Constants ◽  
Lactate Concentration ◽  
Strong Ion Difference ◽  
Training Methods ◽  
Acid Base Balance ◽  
Acid Base ◽  
Independent Variables ◽  
Base Analysis ◽  
Base Balance ◽  
Weak Electrolytes

The acid-base analysis method described by Stewart (1981) was applied to the greyhound, an animal that undergoes large changes in intra- and extracellular hydrogen ion concentrations during a race. Increases in plasma [H+] especially during the first 15 min of recovery, induced by increases in lactate concentration in the plasma, were reduced by lowering of PCO2 (hyperventilation) and removal of Cl− from the plasma. [H+] calculated by the Stewart method is similar to that measured directly with a pH electrode when the strong ion difference is within 10 meq/L of resting values (≈ 40 meqIL); thus the measured independent variables were sufficient to account for the [H+] using the Stewart analysis. When the strong ion difference became lower than 30 meq/L, increased variability between measured and calculated [H+] occurred. An error analysis demonstrated the importance of minimizing measurement error of all independent variables, including as many strong and weak electrolytes as possible in the analyses, using the most accurate dissociation constants possible, and understanding the dissociation behavior of the weak electrolytes, especially the plasma proteins, when using the Stewart analysis. The Stewart method of analyzing acid-base balance can contribute to improved training methods for obtaining maximum exercise performance. Key words: racing greyhound, sprint exercise, strong ion difference, weak electrolytes

Modeling the effects of proteins on pH in plasma

1999 ◽  
Vol 86 (4) ◽  
pp. 1421-1427 ◽  
Author(s):  
Philip D. Watson
Keyword(s):  
Serum Albumin ◽  
Association Constant ◽  
Fixed Charge ◽  
Side Chain ◽  
Weak Acids ◽  
Acid Base Balance ◽  
Acid Base ◽  
Histidine Residues ◽  
Base Balance ◽  
Parameter Values

Stewart’s model of plasma acid-base balance ( Can. J. Physiol. Pharmacol. 61: 1444–1461, 1983) has three weaknesses in the treatment of weak acids: 1) the combination of all weak acids into one entity, 2) inappropriate chemistry for the protein combination with H+, and 3) undocumented values for the dissociation parameters. The present study models serum albumin acid-base properties by fixed negative charges and the association of H+ with the imidazole side chain of histidine. This model has three parameters: 1) the net negative fixed charge (21 eq/mol), 2) the number of histidine residues (16/mol), and 3) the association constant for the imidazole side chain (1.77 × 10−7 eq/l), all determined from published values. The model was compared with that of Figge, Mydosh, and Fencl ( J. Lab. Clin. Med.120: 713–719, 1992) and with the pH data of Figge, Rossing, and Fencl ( J. Lab. Clin. Med. 117: 453–467, 1991). The predictions of pH were excellent, comparable to those found by Figge, Mydosh, and Fencl. The model has the advantages that its structure and parameter values are supported by the literature and that the acid-base effects of factors modifying protein can be investigated.

Cardiorespiratory effects of prolonged angiotensin II block in resting conscious dogs

2001 ◽  
Vol 79 (9) ◽  
pp. 825-830
Author(s):  
Donald B Jennings
Keyword(s):  
Angiotensin Ii ◽  
Salt Water ◽  
Respiratory Control ◽  
Conscious Dogs ◽  
Chow Diet ◽  
Strong Ion Difference ◽  
Ang Ii ◽  
Acid Base Balance ◽  
Acid Base ◽  
Base Balance

Intravenous (iv) infusion of the angiotensin II (ANG II) receptor blocker saralasin in resting conscious dogs during physiological pertubations, such as hypotension and prolonged hypoxia, indicates the presence of an ANG II drive to increase respiration and decrease the arterial partial pressure of CO2 (PaCO2). In contrast, in eupneic resting dogs on a regular chow diet, iv infusion of saralasin for short periods (up to 30 min) provides no evidence of a tonic effect of circulating levels of ANG II on acid-base balance, respiration, metabolism, or circulation. However, ANG II influences physiological processes involving salt, water, and acid-base balances, which are potentially expressed beyond a 30 min time period, and could secondarily affect respiration. Therefore, we tested the hypothesis that blocking ANG II with iv saralasin would affect respiration and circulation over a 4-h period. Contrary to the hypothesis, iv infusion of saralasin in resting conscious eupneic dogs on a regular chow diet over a 4-h period had no effects on plasma strong ions, osmolality, acid-base balance, respiration, metabolism, or circulation when compared with similar control studies in the same animals. Thus, ANG II does not play a tonic modulatory role in respiratory control under "normal" physiological conditions.Key words: acid-base balance, arginine vasopressin, saralasin, strong ions, strong ion difference.

scholarly journals Influence of Acid-Base Balance on Efficacy and Toxicity of Drugs

1965 ◽  
Vol 58 (11P2) ◽  
pp. 961-963 ◽  
Author(s):  
M D Milne
Keyword(s):  
Practical Importance ◽  
Physiological Property ◽  
Water Soluble ◽  
Weak Acids ◽  
Acid Base Balance ◽  
Acid Base ◽  
Urinary Ph ◽  
Alkaline Urine ◽  
Base Balance ◽  
Ph Dependent

Changes in acid-base balance have a profound influence on many aspects of the action of drugs. This is illustrated by data on the absorption of drugs from the stomach and intestine, in changes in distribution of drugs between plasma and cells, and the effect of change in urinary pH. As a general principle, these changes in the pharmacology of weak acids and bases are governed by physicochemical principles, which influence the proportion of the ionized and unionized components according to the pH of the medium and also to the peculiar property of biological membranes which allow the free passage of the lipoid-soluble unionized component and impede transfer of the water-soluble ionized fraction. Lipoid-soluble weak acids are excreted at higher clearances in alkaline urine, and conversely weak bases in acid urine. This is shown to be of practical importance in the treatment of poisoning, in the diagnosis of addiction to drugs and in studies of drug metabolism. In general, the excretion of natural metabolites is less likely to be influenced by urinary pH, as these substances are usually less lipoid-soluble than many widely used drugs. pH-dependent excretion is, however, of practical importance in relation to the urinary content of many indolic metabolites and also in the excretion of pigments derived from the degradation of hæmoglobin. Urobilinogen excretion is certainly pH-dependent, a higher clearance rate occurring in alkaline urine. However, work is necessary to decide whether some of the porphyrins also show this important physiological property.

Effect of chronic acetazolamide administration on gas exchange and acid-base control after maximal exercise

1994 ◽  
Vol 76 (3) ◽  
pp. 1211-1219 ◽  
Author(s):  
J. M. Kowalchuk ◽  
G. J. Heigenhauser ◽  
J. R. Sutton ◽  
N. L. Jones
Keyword(s):  
Gas Exchange ◽  
Muscle Power ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Arterial Lactate ◽  
Arterial Pco2 ◽  
Co2 Output ◽  
Base Balance ◽  
Arterial Plasma

The interaction between systems regulating acid-base balance (i.e., CO2, strong ions, week acids) was studied in six subjects for 10 min after 30 s of maximal isokinetic cycling during control conditions (CON) and after 3 days of chronic acetazolamide (ChACZ) administration (500 mg/8 h po) to inhibit carbonic anhydrase (CA). Gas exchange was measured; arterial and venous forearm blood was sampled for acid-base variables. Muscle power output was similar in ChACZ and CON, but peak O2 intake was lower in ChACZ; peak CO2 output was also lower in ChACZ (2,207 +/- 220 ml/min) than in CON (3,238 +/- 87 ml/min). Arterial PCO2 was lower at rest, and its fall after exercise was delayed in ChACZ. In ChACZ there was a higher arterial [Na+] and lower arterial [lactate-] ([La-]) accompanied by lower arterial [K+] and higher arterial [Cl-] during the first part of recovery, resulting in a higher arterial plasma strong ion difference (sigma [cations] - sigma [anions]). Venoarterial (v-a) differences across the forearm showed a similar uptake of Na+, K+, Cl-, and La- in ChACZ and CON. Arterial [H+] was higher and [HCO3-] was lower in ChACZ. Compared with CON, v-a [H+] was similar and v-a [HCO3-] was lower in ChACZ. Chronic CA inhibition impaired the efflux of CO2 from inactive muscle and its excretion by the lungs and also influenced the equilibration of strong ions.(ABSTRACT TRUNCATED AT 250 WORDS)

Calculation of physiological acid-base parameters in multicompartment systems with application to human blood

2003 ◽  
Vol 95 (6) ◽  
pp. 2333-2344 ◽  
Author(s):  
E. Wrenn Wooten
Keyword(s):  
Base Change ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Base Parameters ◽  
Present Formalism ◽  
Base Balance ◽  
Multicompartment Systems ◽  
Relationship Of ◽  
The Relationship

A general formalism for calculating parameters describing physiological acid-base balance in single compartments is extended to multicompartment systems and demonstrated for the multicompartment example of human whole blood. Expressions for total titratable base, strong ion difference, change in total titratable base, change in strong ion difference, and change in Van Slyke standard bicarbonate are derived, giving calculated values in agreement with experimental data. The equations for multicompartment systems are found to have the same mathematical interrelationships as those for single compartments, and the relationship of the present formalism to the traditional form of the Van Slyke equation is also demonstrated. The multicompartment model brings the strong ion difference theory to the same quantitative level as the base excess method.

630: Strong ion difference in fetal cord blood - A novel comprehensive approach to acid-base balance

2007 ◽  
Vol 197 (6) ◽  
pp. S182
Author(s):  
Yoni Cohen ◽  
Jessica Ascher Landsberg ◽  
Michael Kupferminc ◽  
Joseph B. Lessing ◽  
Adi Nimrod ◽  
...  
Keyword(s):  
Cord Blood ◽  
Comprehensive Approach ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Fetal Cord Blood ◽  
Base Balance
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