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Biomedical subjects

R F Burton

Publications and source records attributed to R F Burton.

13 recordsLinked to original sources
PubMed1992

The roles of intracellular buffers and bone mineral in the regulation of acid-base balance in mammals.

1. Regulation of intracellular and extracellular pH may conflict in their requirements for movement of acid or base. 2. Cells make a positive or a negative contribution to 'tissue buffering' of extracellular fluid (ECF), depending on their internal buffer value, on the tightness of their internal pH control by membrane mechanisms, and on the nature of the acid-base disturbance. 3. A role is suggested for electrogenic Na-HCO3 co-transport in some of the ion shifts that occur in acid-base disturbances. 4. The time course of 'tissue buffering' in nephrectomized mammals in hypercapnia is variable, and it is far from clear in intact, unanaesthetized mammals. 5. Buffering of ECF by Ca salts of bone mineral in acidosis can only be substantial if accompanied by Ca excretion; the release of HCO3 with Na and K is more significant. 6. The relative importance of cells and of bone mineral in the buffering of ECF is unclear.

Acid-Base Equilibrium↗
PubMed1992

Relative changes in salivary Na+ and K+ concentrations relating to stress induction.

Three independent studies are reported in which periods of "relaxation" (A) and presumed stressors (B) were given to female students in an ABA design. The "stressors" were: (1) obligatory time-wasting activity; (2) a mental "IQ" test; and (3) delivering a speech. Saliva was collected immediately after "relaxation" and "stress" periods. "Stress" and "arousal" state were retrospectively assessed in experiments (1) and (2) by subject self-rating and in experiment 1 also by trained observers for the periods A and B. The molar [K+/Na+] ratio was determined for each saliva sample. The prediction that [K+/Na+] would increase with stress induction was supported by statistically significant results with stressors 1 and 2 (p less than 0.01), but speech delivery (3) resulted in a significant rise of [K+/Na+] after the stressor period. Correlations between [K+/Na+] and "stress" and "arousal" ratings also substantiated the prediction.

Adolescent↗
PubMed1992

Clarification of the concept of psychological stress ("psystress").

The concept of "stress" in the current academic literature is unstandardized, and therefore confusing. The theoretical approach of regarding stress as an intervening variable seems most generally agreed on by researchers; the unambiguous term "Psystress" proposal to denote the mental state involved. Aspects of vocabulary concerning psystress production and response are also discussed.

Adaptation, Psychological↗
PubMed1988

The protein content of extracellular fluids and its relevance to the study of ionic regulation: net charge and colloid osmotic pressure.

1. Protein net charge in blood plasma and haemolymph is relevant to overall anion-cation balance, Donnan equilibria, colloid osmotic pressures (COPs), buffering and liquid junction potentials, but its definition and measurement are not always straightforward. 2. Normal values of protein net charge in man and other animals are discussed, as is their dependence on pH. 3. Although it is clear that charge on a protein augments COP, the theory of COP is still incomplete. 4. The dependence of COP on protein and salt concentrations and on pH are therefore considered empirically. 5. Normal values for COP in various animals are given and the regulation of COP is discussed.

Acid-Base Equilibrium↗
PubMed1987

On calculating concentrations of "HCO3" from pH and PCO2.

1. As used in the Henderson-Hasselbalch equation, [HCO3], [CO2] and pH may all be variously defined; values of pK'1 must be chosen accordingly. 2. In common usage, "HCO3" may include CO3, carbamate, various ion pairs and possibly other bound CO2, as well as free HCO3 ions. 3. pH measurements may be systematically affected by the choice of standard buffers and by proteins and blood cells, and the errors in pH may be pH-dependent. 4. According to how it is expressed, the solubility coefficient for CO2 (S) may be influenced by sample water content, proteins and lipids. However, it need not feature in the calculation. 5. pK'1 is often found to decrease with increasing pH. This may be partly due to inclusion of CO3 and carbamate, but not of H2CO3.HCO3-, in "HCO3" and partly, perhaps, to errors in pH measurement. 6. To the extent that pH measurements are reliable, concentrations or activities of true HCO3 are calculable from pH and PCO2, but, if pH measurements are likely to be systematically erroneous, it may be preferable to define "HCO3" as "total bound CO2" and to base pK'1 on gasometric or titrimetric determinations of that.

Animals↗
PubMed1986

Ionic regulation in fish: the influence of acclimation temperature on plasma composition and apparent set points.

Published data on the influence of acclimation temperature on normal ionic concentrations in fish plasma are summarized. Although osmolality rises near 0 degree C in many marine fish, there is otherwise no general tendency in marine species for osmolality, Na and Cl to fall with increasing temperature. The suggestion that osmolality, Na and Cl in freshwater fish typically fall with decreasing temperature is not supported. K and Ca generally rise with increasing temperature, or stay constant. Mg generally falls with increasing temperature, or stays constant. Evidence on concomitant variations in set points is sparse, but apparent set points for osmolality/Na/Cl, except near 0 degree C, usually vary by less than +/- 2% degrees C-1.

Acclimatization↗
PubMed1986

The role of imidazole ionization in the control of breathing.

Interacting effects of pH and temperature on ventilation in turtles and alligators have suggested that pH is monitored in terms of imidazole ionization, but the view that this is true in alligators and ectotherms generally has been attacked. Published evidence re-interpreted here indicates that this "alphastat control" could indeed operate in turtles, alligators, chickens (i.e. intrapulmonary chemoreceptors) and perhaps cats. Nevertheless, studies on temperature effects cannot distinguish with certainty between imidazole and some amino groups in this context.

Alligators and Crocodiles↗
PubMed1986

Internal reference standards in ionic regulation and the predictability of ionic concentrations in animals.

The regulation of ions at similar concentrations in most individuals of a species suggests the existence of internal reference standards. Few have been identified, but many probably relate to cell membrane properties, including potentials, surface charge densities and equilibrium constants of receptor molecules. Solubility may sometimes determine the product [Ca2+] [CO2-3]. Reference standards must generally each relate to more than one ionic species. For some concentrations, including osmolality, there may be no direct reference standard.

Acid-Base Equilibrium↗
PubMed1978

Intracellular buffering.

In the quantification of buffering the distinct roles of bicarbonate and of other buffers must be taken into account. The determination of the total non-bicarbonate buffer value, betaa, in intact tissues is complicated by active pH regulation and by heterogeneity of cytoplasm with respect to betaa, while heterogeneity with respect to pH in vivo could cause errors in estimates made with homogenates. Available estimates of betaa are discussed, as are the individual contributions of proteins, dipeptides and phosphates. A high betaa is appropriate in cells which sometimes have high rates of glycolysis, or which buffer extracellular fluid, but non-protein buffer concentrations can be well below the limits imposed by osmolarity, perhaps because buffering can upset ionic gradients.

Acid-Base Equilibrium↗
PubMed1976

The mobilization of calcium and bicarbonate by raised concentrations of potassium in the haemolymph of the snail, Helix pomatia.

1. After the concentration of potassium in the haemolymph of Helix pomatia has been raised by the infusion of KCl, it falls approximately exponentially for a time and then tends to rise. The accompanying rise and fall of calcium concentration can be fitted to a simple mathematical model. 2. The mobilization of calcium is accompanied by the generation of bicarbonate in equivalent amounts, without much change in pH or Pco2. 3. There is probably an increased production or retention of carbon dioxide at this time, but the main cause of the changes in calcium and bicarbonate is not respiratory acidosis. 4. The concentration of potassium rises in snalis that have been infused with CaCl2. 5. The adverse responses visible in snails infused with KCl are largely prevented when CaCl2 is infused at the same time. 6. Homeostasis seems to involve the maintenance of a proper balance of calcium and potassium concentrations.

Animals↗