Physicochemical analysis of phasic menstrual cycle effects on acid-base balance

2001 ◽  
Vol 280 (2) ◽  
pp. R481-R487 ◽  
Author(s):  
Robert J. Preston ◽  
Aaron P. Heenan ◽  
Larry A. Wolfe
Keyword(s):  
Menstrual Cycle ◽  
Ventilatory Threshold ◽  
Physicochemical Analysis ◽  
Carbon Dioxide Tension ◽  
Weak Acid ◽  
Ion Concentration ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Hydrogen Ion Concentration ◽  
Base Balance

In accordance with Stewart's physicochemical approach, the three independent determinants of plasma hydrogen ion concentration ([H+]) were measured at rest and during exercise in the follicular (FP) and luteal phase (LP) of the human menstrual cycle. Healthy, physically active women with similar physical characteristics were tested during either the FP ( n = 14) or LP ( n = 14). Arterialized blood samples were obtained at rest and after 5 min of upright cycling at both 70 and 110% of the ventilatory threshold (TVent). Measurements included plasma [H+], arterial carbon dioxide tension (PaCO2 ), total weak acid ([ATot]) as reflected by total protein, and the strong-ion difference ([SID]). The transition from rest to exercise in both groups resulted in a significant increase in [H+] at 70% TVentversus rest and at 110% TVent versus both rest and 70% TVent. No significant between-group differences were observed for [H+] at rest or in response to exercise. At rest in the LP, [ATot] and PaCO2 were significantly lower (acts to decrease [H+]) compared with the FP. This effect was offset by a reduction in [SID] (acts to increase [H+]). After the transition from rest to exercise, significantly lower [ATot] during the LP was again observed. Although the [SID] and PaCO2 were not significantly different between groups, trends for changes in these two variables were similar to changes in the resting state. In conclusion, mechanisms regulating [H+] exhibit phase-related differences to ensure [H+] is relatively constant regardless of progesterone-mediated ventilatory changes during the LP.

Origins of [H+] Changes in Exercising Skeletal Muscle

1995 ◽  
Vol 20 (3) ◽  
pp. 357-368 ◽  
Author(s):  
Michael I. Lindinger
Keyword(s):  
Skeletal Muscle ◽  
High Intensity ◽  
Total Concentration ◽  
High Intensity Exercise ◽  
Ion Concentration ◽  
Strong Ion Difference ◽  
Mammalian Skeletal Muscle ◽  
Acid Base Balance ◽  
Hydrogen Ion Concentration ◽  
Base Balance

This brief review describes the main physicochemical factors that contribute to increases in intracellular hydrogen ion concentration ([H+]i) in mammalian skeletal muscle during high intensity exercise. High intensity exercise results in changes in the three main independent physicochemical variables: PCO2, the strong ion difference ([SID]), and total concentration of weak acids and bases ([Atot]), within the intracellular fluid compartment of contracting muscle that result in increased [H+]i. The decrease in [SID] contributes 62% to the increase in [H+]i, due to decreased [K+]i and increased [lactate]i; the decrease in phosphocreatine ([PCr2−]i) exerts an alkalinizing effect. The increase in [Atot], resulting primarily from increases in inorganic phosphate and creatine as a result of PCr2− breakdown, contributes 19% to the increase in [H+]i. An increase in the apparent proton dissociation constant (KA) for [Atot] contributes 7% to the increase in [H+]i. PCO2 is a relatively poor effector of changes in [H+]i, such that a 50-mmHg increase in PCO2 contributes only 12% to the increase in [H+]i during high intensity exercise. Key words: acid-base balance, strong ion difference, phosphocreatine, potassium, carbon dioxide, metabolism

Plasma acid-base regulation above and below ventilatory threshold in late gestation

2000 ◽  
Vol 88 (1) ◽  
pp. 149-157 ◽  
Author(s):  
Aaron P. Heenan ◽  
Larry A. Wolfe
Keyword(s):  
Ventilatory Threshold ◽  
Weak Acid ◽  
Late Gestation ◽  
Ion Concentration ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Hydrogen Ion Concentration ◽  
Exercise Induced ◽  
Induced Changes ◽  
Physicochemical Approach

Stewart's physicochemical approach was used to study the effects of pregnancy on acid-base regulation in arterialized blood. Responses of 15 healthy pregnant women (PG; gestational age, 37.1 ± 0.2 wk) were compared with those of 15 nonpregnant controls (CG) at rest and during cycling at 70 and 110% of the ventilatory threshold (Tvent). Hydrogen ion concentration ([H+]) was lower in the PG vs. CG at rest and during exercise ( P < 0.05 at rest and 70% Tvent). Exercise-induced changes in [H+] were similar between groups. Lower resting [H+] values in the PG vs. CG resulted from lower values for arterialized [Formula: see text]([Formula: see text]) and total weak acid ([A]tot), which were partly offset by a lower strong-ion difference ([SID]). Reductions in [A]tot and [SID] at rest were primarily the result of reductions in albumin [Alb] and sodium [Na+], respectively. In the transition from rest to 70% Tvent, small increases in[Formula: see text] and [A]totcontributed to moderate increases in [H+] in both groups, however [SID] increased in the PG and decreased in the CG ( P < 0.05 between groups). In the transition from rest to 110% Tvent, decreases in [SID] made a significantly greater contribution to changes in [H+] in the CG vs. PG. Exercise-induced increases in [H+] are similar in the pregnant vs. nonpregnant state, but there is a reduced contribution of [SID] both above and below Tvent during pregnancy.

Role of peripheral chemoreceptors and central chemosensitivity in the regulation of respiration and circulation.

1982 ◽  
Vol 100 (1) ◽  
pp. 23-40 ◽  
Author(s):  
R G O'Regan ◽  
S Majcherczyk
Keyword(s):  
The Body ◽  
Ion Concentration ◽  
Regulation Of Respiration ◽  
Acid Base Balance ◽  
Acid Base ◽  
Vascular Effects ◽  
Peripheral Chemoreceptor ◽  
Hydrogen Ion Concentration ◽  
Central Chemosensitivity ◽  
Base Balance

Adjustments of respiration and circulation in response to alterations in the levels of oxygen, carbon dioxide and hydrogen ions in the body fluids are mediated by two distinct chemoreceptive elements, situated peripherally and centrally. The peripheral arterial chemoreceptors, located in the carotid and aortic bodies, are supplied with sensory fibres coursing in the sinus and aortic nerves, and also receive sympathetic and parasympathetic motor innervations. The carotid receptors, and some aortic receptors, are essential for the immediate ventilatory and arterial pressure increases during acute hypoxic hypoxaemia, and also make an important contribution to respiratory compensation for acute disturbances of acid-base balance. The vascular effects of peripheral chemoreceptor stimulation include coronary vasodilation and vasoconstriction in skeletal muscle and the splanchnic area. The bradycardia and peripheral vasoconstriction during carotid chemoreceptor stimulation can be lessened or reversed by effects arising from a concurrent hyperpnoea. Central chemoreceptive elements respond to changes in the hydrogen ion concentration in the interstitial fluid in the brain, and are chiefly responsible for ventilatory and circulatory adjustments during hypercapnia and chronic disturbances of acid-base balance. The proposal that the neurones responsible for central chemoreception are located superficially in the ventrolateral portion of the medulla oblongata is not universally accepted, mainly because of a lack of convincing morphological and electrophysiological evidence. Central chemosensitive structures can modify peripheral chemoreceptor responses by altering discharges in parasympathetic and sympathetic nerves supplying these receptors, and such modifications could be a factor contributing to ventilatory unresponsiveness in mild hypoxia. Conversely, peripheral chemoreceptor drive can modulate central chemosensitivity during hypercapnia.

scholarly journals Acid-Base Balance in Callinectes Sapidus During Acclimation from High to Low Salinity

1982 ◽  
Vol 101 (1) ◽  
pp. 255-264 ◽  
Author(s):  
RAYMOND P. HENRY ◽  
JAMES N. CAMERON
Keyword(s):  
Carbonic Anhydrase ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Ion Regulation ◽  
Low Salinity ◽  
Base Balance

When transferred from 865 to 250 m-osmol salinity, the blue crab C. sapidus maintains its blood Na+ and Cl− concentrations significantly above those in the medium. When branchial carbonic anhydrase is inhibited by acetazolamide, ion regulation fails and the animals do not survive the transfer. An alkalosis occurs in the blood at low salinity, indicated by an increase in HCO3− and pH at constant PCO2. The alkalosis is closely correlated with an increase in the Na+-Cl− difference, a convenient indicator of the overall strong ion difference. The contribution of changes in PCO2 to acid-base changes was negligible, but the change in the total weak acid (proteins) may be important. It is suggested that the change in blood acidbase status with salinity is related to an increase in the strong ion difference, which changes during the transition from osmoconformity to osmoregulation in the blue crab, and which is related to both carbonic anhydrase and ionactivated ATPases. Note:

Physicochemical analysis of acid–base responses to prolonged moderate exercise in late gestation

2006 ◽  
Vol 31 (6) ◽  
pp. 744-752 ◽  
Author(s):  
Sarah A. Charlesworth ◽  
Larry A. Wolfe ◽  
Gregory A.L. Davies
Keyword(s):  
Pregnant Women ◽  
Ventilatory Threshold ◽  
Late Gestation ◽  
Ion Concentration ◽  
Occupational Activity ◽  
Strong Ion Difference ◽  
Moderate Exercise ◽  
Acid Base ◽  
Experimental Conditions ◽  
Hydrogen Ion Concentration

Stewart’s physicochemical approach was employed to investigate the safety of an average recreational and occupational activity (prolonged moderate exercise) on maternal acid–base homeostasis. The responses of 10 healthy, physically active pregnant women (PG, gestational age 34–38 weeks) were compared with those of 10 non-pregnant female controls (CG). Subjects cycled for 40 min at 85% of their measured ventilatory threshold (VT). During the transition from rest to exercise, hydrogen ion concentration ([H+]) increased significantly and bicarbonate concentration ([HCO3–]) decreased significantly in both groups. Total weak acid ([Atot]) increased significantly with exercise in both groups, whereas the strong ion difference ([SID]) and CO2 tension (PaCO2) did not change significantly with exercise. Values for [H+], [HCO3–], PaCO2, [Atot] and [SID] were significantly lower in the PG vs. CG under all experimental conditions. Acid–base responses to prolonged moderate exercise are quantitatively similar in the pregnant vs. non-pregnant state. However, pregnant women maintain a lower plasma [H+] (approximately 3 neq/L (1 neq/L = 1 nmol/L)) throughout rest, exercise, and recovery, as a result of lower values for PaCO2 and [Atot], which is partly offset by a lower [SID]. The results indicate that prolonged moderate exercise appears to be well tolerated by healthy recreationally and occupationally active pregnant women.

Physicochemical analysis of acid–base status during recovery from high-intensity exercise in Standardbred racehorses

2005 ◽  
Vol 2 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Amanda Waller ◽  
Michael I Lindinger
Keyword(s):  
High Intensity ◽  
Venous Blood ◽  
Physicochemical Analysis ◽  
High Intensity Exercise ◽  
Ion Concentration ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Acid Base Status ◽  
Standardbred Racehorses

AbstractThe present study used the physicochemical approach to characterize the changes in acid–base status that occur in Standardbred racehorses during recovery from high-intensity exercise. Jugular venous blood was sampled from nine Standardbreds in racing condition, at rest and for 2 h following a high-intensity training workout. Plasma [H+] increased from 39.1±1.0 neq l−1 at rest to 44.8±2.7 neq l−1 at 1 min of recovery. A decreased strong ion difference ([SID]) was the primary contributor to the increased [H+] immediately at the end of exercise, while increased plasma weak ion concentration ([Atot]) was a minor contributor to the acidosis. A decreased partial pressure of carbon dioxide (PCO2) at 1 min of recovery had a slight alkalinizing effect. The decreased [SID] at 1 min of recovery was a result of a 15.1±3.1 meq l−1 increase in [lactate−], as [Na+] and [K+] were also increased by 6.5±0.7 and 1.14±0.06 meq l−1, respectively, at 1 min of recovery. It is concluded that high-intensity exercise and recovery is associated with significant changes in acid–base balance, and that full recovery of many parameters that determine acid–base status requires 60–120 min.

Acid-base balance in ducks (Anas platyrhynchos) during involuntary submergence

1987 ◽  
Vol 252 (2) ◽  
pp. R348-R352 ◽  
Author(s):  
M. Shimizu ◽  
D. R. Jones
Keyword(s):  
Protein Content ◽  
Total Protein ◽  
Recovery Period ◽  
Lactate Production ◽  
Weak Acid ◽  
Total Protein Content ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Base Balance

Measurements of all the major independent variables [arterial CO2 tension (PaCO2); strong-ion difference ([SID]), and total protein content, which approximate total weak acid concentration in plasma] are essential for understanding changes in acid-base balance in plasma. During involuntary submergence of 1, 2, or 4 min, PaCO2 in ducks increased and arterial pH (pHa) decreased. During 1-min dives there were no significant changes in any strong ions. In both 2- and 4-min dives, there was a significant increase in [lactate-], but because of an increase in equal magnitude of [Na+], [SID] did not change. During recovery from all dives the plasma remained acidotic for several minutes, although PaCO2 fell below predive levels in less than 1 min. [Lactate-] increased in the recovery period. There were no changes in total protein content during submergence or recovery. Breathing 100% O2 before 2-min dives caused a reduction in [lactate-] production and release during and after the dive, although due to a marked increased in PaCO2, pHa fell as low as in 4-min dives after breathing air. After 1 min of recovery, pHa returned to normal along with the restoration of the predive level of PaCO2. We conclude that the acidosis during involuntary submergence is due solely to an increase in PaCO2, whereas in recovery it is caused by decreased [SID].

Disorders of acid–base balance

2018 ◽  
Author(s):  
Aron Chakera ◽  
William G. Herrington ◽  
Christopher A. O’Callaghan
Keyword(s):  
The Body ◽  
Ion Concentration ◽  
Acid Base Balance ◽  
Acid Base ◽  
Compensatory Mechanisms ◽  
Urine Ph ◽  
Hydrogen Ion Concentration ◽  
Normal Metabolism ◽  
Base Balance ◽  
Ph Scale

Normal metabolism results in a net acid production of approximately 1 mmol/kg day−1. Physiological pH is regulated by excretion of this acid load (as carbon dioxide) by the kidneys and the lungs. A series of buffers in the body reduces the effects of metabolic acids on body and urine pH. For acid–base disorders to occur, there must be excessive intake (or loss) of acid (or base) or, alternatively, an inability to excrete acid. For these changes to result in a substantially abnormal pH, the various buffer systems must been overwhelmed. The pH scale is logarithmic, so relatively small changes in pH signify large differences in hydrogen ion concentration. Most minor perturbations in acid–base balance are asymptomatic, as small changes in acid or base levels are rapidly controlled through consumption of buffers or through changes in respiratory rate. Alterations in renal acid excretion take some time to occur. Only when these compensatory mechanisms are overwhelmed do symptoms related to changes in pH develop. This chapter reviews the causes and consequences of acid–base disorders.

Renal handling of α-ketoglutarate by the dog

1964 ◽  
Vol 207 (2) ◽  
pp. 483-494 ◽  
Author(s):  
Sulamita Balagura ◽  
Robert F. Pitts
Keyword(s):  
Metabolic Alkalosis ◽  
Renal Excretion ◽  
Respiratory Acidosis ◽  
Respiratory Alkalosis ◽  
Ion Concentration ◽  
Acid Base Balance ◽  
Renal Handling ◽  
Hydrogen Ion Concentration ◽  
Tubular Lumen ◽  
Base Balance

Renal excretion, reabsorption, utilization, and peritubular transport of α-ketoglutarate were measured in the anesthetized dog under conditions of normal acid-base balance and in metabolic and respiratory acidosis and alkalosis. In the normal dog, the reabsorption of α-ketoglutarate is Tm limited. Chronic metabolic acidosis, induced by the feeding of ammonium chloride, and acute respiratory acidosis, induced by breathing CO2-O2 mixtures, increase Tm values significantly. Acute respiratory alkalosis, induced by hyperventilation and acute metabolic alkalosis, induced by the infusion of THAM (tris (hydroxymethyl) aminomethane), reduce Tm values significantly. Comparable states of acute metabolic alkalosis, induced by the infusion of sodium bicarbonate, do not reduce Tm to an extent comparable to that induced by hyperventilation or the infusion of TIIAM. For a variety of reasons, Tm of α-ketoglutarate seems to be more responsive to changes in intracellular than in extracellular hydrogen ion concentration. Transport of α-ketoglutarate into tubular cells both from tubular lumen and from peritubular fluid is probably active, i.e., against electrochemical gradients. It is suggested that both processes are affected by alterations of pH of intracellular fluid.

Sign in / Sign up

Export Citation Format

Share Document