Trans-cerebral HCO3− and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans

2021 ◽  
pp. 0271678X2110659
Author(s):  
Hannah G Caldwell ◽  
Ryan L Hoiland ◽  
Kurt J Smith ◽  
Patrice Brassard ◽  
Anthony R Bain ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Respiratory Acidosis ◽  
Carbon Dioxide Tension ◽  
Acid Base Balance ◽  
Acid Base ◽  
Cycling Exercise ◽  
Net Uptake ◽  
Base Balance ◽  
Exercise Induced ◽  
Net Release

This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3−]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3−] increased by 0.15 ± 0.05 mmol ⋅ l−1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3−] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3−] exchange (CBF × venous-arterial [HCO3−] difference) was reduced indicating a shift from net release toward net uptake of [HCO3−] (P = 0.004). Arterial [HCO3−] was reduced by −0.48 ± 0.15 mmol ⋅ l−1 per nmol ⋅ l−1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3−] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3−] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3−] – during acute respiratory/exercise-induced metabolic acidosis, respectively – differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3−] exchange).

Effect of systemic acid-base balance on ileal secretion

1987 ◽  
Vol 253 (3) ◽  
pp. G330-G335
Author(s):  
D. S. Goldfarb ◽  
P. M. Ingrassia ◽  
A. N. Charney
Keyword(s):  
Metabolic Acidosis ◽  
Cholera Toxin ◽  
Metabolic Disorders ◽  
Respiratory Acidosis ◽  
Secretory Process ◽  
Sprague Dawley ◽  
Acid Base Balance ◽  
Acid Base ◽  
Ph Change ◽  
Base Balance

We previously reported that systemic pH and HCO3 concentration affect ileal water and electrolyte absorption. To determine whether these effects could influence an ongoing secretory process, we measured transport in ileal loops exposed to either saline or 50-75 micrograms cholera toxin in mechanically ventilated Sprague-Dawley rats anesthetized with pentobarbital sodium. The effects of acute respiratory and metabolic acidosis and alkalosis were then examined. Decreases in systemic pH during respiratory acidosis caused equivalent increases in net water (54 +/- 8 microliters . cm-1 . h-1) and Na absorption (7 +/- 1 mu eq . cm- . h-1) and smaller increases in Cl absorption in cholera toxin compared with saline loops. These increases reversed the net secretion of these ions observed during alkalemia in the cholera toxin loops to net absorption. Metabolic acidosis and alkalosis and respiratory compensation of systemic pH of these metabolic disorders also altered cholera toxin-induced secretion in a direction consistent with the pH change. The increase in net HCO3 secretion caused by cholera toxin was unaffected by the respiratory disorders and did not vary with the HCO3 concentration in the metabolic disorders. These findings suggest that the systemic acid-base disorders that characterize intestinal secretory states may themselves alter intestinal absorptive function and fluid losses.

Evaluation of bicarbonate transport in rat distal tubule: effects of acid-base status

1982 ◽  
Vol 243 (4) ◽  
pp. F335-F341 ◽  
Author(s):  
M. S. Lucci ◽  
L. R. Pucacco ◽  
N. W. Carter ◽  
T. D. DuBose
Keyword(s):  
Metabolic Acidosis ◽  
Respiratory Acidosis ◽  
Distal Tubule ◽  
Bicarbonate Transport ◽  
Acid Base Balance ◽  
Acid Base ◽  
Bicarbonate Reabsorption ◽  
Base Balance ◽  
Acid Base Status ◽  
Acute Metabolic Acidosis

Previous micropuncture studies utilizing indirect methods to estimate bicarbonate transport in the rat superficial distal tubule have indicated that the distal bicarbonate reabsorptive process normally operates well below the saturation level. Recent studies from our laboratory failed to demonstrate a spontaneous acid disequilibrium pH in this segment, implying that the bicarbonate reabsorptive rate was less than previously estimated. The purpose of the present experiments were 1) to measure the rate of absolute bicarbonate reabsorption by the rat superficial distal tubule while controlling bicarbonate delivery, and 2) to examine the effects of alterations in acid-base status on the rate of bicarbonate reabsorption. Five groups of rats in different states of acid-base balance were studied. No significant bicarbonate reabsorption was detected in the control hydropenic, combined respiratory acidosis-metabolic alkalosis, acute respiratory acidosis, or acute metabolic acidosis groups. In contrast, metabolic acidosis of 3 days duration resulted in a significant bicarbonate reabsorptive rate of 52.6 +/- 13.9 pmol . mm-1 . min-1. The observation of significant bicarbonate reabsorption in the distal tubule only during chronic metabolic acidosis of 3 days duration is compatible with adaptation of this normally low-capacity segment to chronic changes in systemic acid-base states.

Effects of Acute Changes in Acid-Base Balance on Renal Calcium Excretion in Dogs

1957 ◽  
Vol 191 (2) ◽  
pp. 384-387 ◽  
Author(s):  
Billy James Williamson ◽  
Smith Freeman
Keyword(s):  
Carbon Dioxide ◽  
Metabolic Alkalosis ◽  
Respiratory Acidosis ◽  
Carbon Dioxide Tension ◽  
Calcium Excretion ◽  
Acid Base Balance ◽  
Acid Base ◽  
Calcium Reabsorption ◽  
Base Balance ◽  
Acute Changes

The effects of acute disturbances in acid-base balance on renal cation excretion were studied in dogs. Special attention was given to the excretory mechanism for calcium. Four different states were produced experimentally: respiratory acidosis, metabolic acidosis, metabolic alkalosis and compensated metabolic alkalosis. Additional experiments were carried out in normal and alkalotic animals subjected to calcium loading. Calcium reabsorption was found to vary directly with the filtered load of calcium. The increased excretion of calcium in acidosis appears to be due to an increase in filtered calcium. The percentage of reabsorption of filtered calcium was 98–99% in normal and acidotic dogs, but decreased to approximately 90% in animals made acutely alkalotic. However, the relative loss of water to calcium in the urine in acute alkalosis was decreased, resulting in an elevated renal threshold of retention of calcium in metabolic alkalosis. Data are included on the behavior of inorganic phosphate in the various states studied. Elevated carbon dioxide tension was associated with phosphate mobilization from the tissues regardless of whether or not the carbon dioxide excess was compensated for by extra alkali.

Acid-base balance and plasma composition in the aestivating lungfish (Protopterus)

1977 ◽  
Vol 232 (1) ◽  
pp. R10-R17 ◽  
Author(s):  
R. G. DeLaney ◽  
S. Lahiri ◽  
R. Hamilton ◽  
P. Fishman
Keyword(s):  
Plasma Osmolality ◽  
Respiratory Acidosis ◽  
Electrolyte Balance ◽  
Plasma Composition ◽  
Total Plasma ◽  
Acid Base Balance ◽  
Acid Base ◽  
Plasma Bicarbonate ◽  
Arterial Ph ◽  
Base Balance

Upon entering into aestivation, Protopterus aethiopicus develops a respiratory acidosis. A slow compensatory increase in plasma bicarbonate suffices only to partially restore arterial pH toward normal. The cessation of water intake from the start of aestivation results in hemoconcentration and marked oliguria. The concentrations of most plasma constituents continue to increase progressively, and the electrolyte ratios change. The increase in urea concentration is disproportionately high for the degree of dehydration and constitutes an increasing fraction of total plasma osmolality. Acid-base and electrolyte balance do not reach a new equilibrium within 1 yr in the cocoon.

Effects of temperature on acid-base balance and ventilation in desert iguanas

1981 ◽  
Vol 51 (2) ◽  
pp. 452-460 ◽  
Author(s):  
P. E. Bickler
Keyword(s):  
Steady State ◽  
Pulmonary Ventilation ◽  
Respiratory Acidosis ◽  
Lung Ventilation ◽  
Acid Base Balance ◽  
Acid Base ◽  
Arterial Ph ◽  
Blood Relative ◽  
Base Balance ◽  
History Of

The effects of constant and changing temperatures on blood acid-base status and pulmonary ventilation were studied in the eurythermal lizard Dipsosaurus dorsalis. Constant temperatures between 18 and 42 degrees C maintained for 24 h or more produced arterial pH changes of -0.0145 U X degrees C-1. Arterial CO2 tension (PCO2) increased from 9.9 to 32 Torr plasma [HCO-3] and total CO2 contents remained constant at near 19 and 22 mM, respectively. Under constant temperature conditions, ventilation-gas exchange ratios (VE/MCO2 and VE/MO2) were inversely related to temperature and can adequately explain the changes in arterial PCO2 and pH. During warming and cooling between 25 and 42 degrees C arterial pH, PCO2 [HCO-3], and respiratory exchange ratios (MCO2/MO2) were similar to steady-state values. Warming and cooling each took about 2 h. During the temperature changes, rapid changes in lung ventilation following steady-state patterns were seen. Blood relative alkalinity changed slightly with steady-state or changing body temperatures, whereas calculated charge on protein histidine imidazole was closely conserved. Cooling to 17-18 degrees C resulted in a transient respiratory acidosis correlated with a decline in the ratio VE/MCO2. After 12-24 h at 17-18 degrees C, pH, PCO2, and VE returned to steady-state values. The importance of thermal history of patterns of acid-base regulation in reptiles is discussed.

scholarly journals ASSOCIATION OF ACID-BASE PARAMETERS WITH LACTATE LEVEL IN CRITICALLY ILL PATIENTS WITH METABOLIC ACIDOSIS

2018 ◽  
Vol 24 (2) ◽  
pp. 141
Author(s):  
Donaliazarti Donaliazarti ◽  
Rismawati Yaswir ◽  
Hanifah Maani ◽  
Efrida Efrida
Keyword(s):  
Metabolic Acidosis ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Lactate Level ◽  
Linear Regression Analysis ◽  
P Value ◽  
Acid Base Balance ◽  
Acid Base ◽  
Base Parameters ◽  
Base Balance

Metabolic acidosis is prevalent among critically ill patients and the common cause of metabolic acidosis in ICU is lactic acidosis. However, not all ICUs can provide lactate measurement. The traditional method that uses Henderson-Hasselbach equation (completed with BE and AG) and alternative method consisting of Stewart and its modification (BDEgap and SIG), are acid-base balance parameters commonly used by clinicians to determine metabolic acidosis in critically ill patients. The objective of this study was to discover the association between acid-base parameters (BE, AGobserved, AGcalculated, SIG, BDEgap) with lactate level in critically ill patients with metabolic acidosis. This was an analytical study with a cross-sectional design. Eighty-four critically ill patients hospitalized in the ICU department Dr. M. Djamil Padang Hospital were recruited in this study from January to September 2016. Blood gas analysis and lactate measurement were performed by potentiometric and amperometric method while electrolytes and albumin measurement were done by ISE and colorimetric method (BCG). Linear regression analysis was used to evaluate the association between acid-base parameters with lactate level based on p-value less than 0.05. Fourty five (54%) were females and thirty-nine (46%) were males with participant’s ages ranged from 18 to 81 years old. Postoperative was the most reason for ICU admission (88%). Linear regression analysis showed that p-value for BE, AGobserved, AGcalculated, SIG and BDEgap were 119; 0.967; 0.001; 0.001; 0.689, respectively. Acid-base balance parameters which were mostly associated with lactate level in critically ill patients with metabolic acidosis were AGcalculated and SIG. 

The effects of enforced activity on ventilation, circulation and blood acid-base balance in the aquatic gill-less urodele, Cryptobranchus alleganiensis; a comparison with the semi-terrestrial anuran, Bufo marinus

1980 ◽  
Vol 84 (1) ◽  
pp. 289-302
Author(s):  
R. G. Boutilier ◽  
D. G. McDonald ◽  
D. P. Toews
Keyword(s):  
Recovery Period ◽  
Respiratory Acidosis ◽  
Bufo Marinus ◽  
Acid Base Balance ◽  
Acid Base ◽  
Post Exercise ◽  
Arterial Blood ◽  
Cryptobranchus Alleganiensis ◽  
Base Balance ◽  
Lower Magnitude

A combined respiratory and metabolic acidosis occurs in the arterial blood immediately following 30 min of strenuous activity in the predominantly skin-breathing urodele, Cryptobranchus alleganiensis, and in the bimodal-breathing anuran, Bufo marinus, at 25 degrees C. In Bufo, the bulk of the post-exercise acidosis is metabolic in origin (principally lactic acid) and recovery is complete within 4-8 h. In the salamander, a lower magnitude, longer duration, metabolic acid component and a more pronounced respiratory acidosis prolong the recovery period for up to 22 h post-exercise. It is suggested that fundamental differences between the dominant sites for gas exchange (pulmonary versus cutaneous), and thus in the control of respiratory acid-base balance, may underline the dissimilar patterns of recovery from exercise in these two species.

Effects of acute and chronic acetazolamide on resting ventilation and ventilatory responses in men

1993 ◽  
Vol 74 (1) ◽  
pp. 230-237 ◽  
Author(s):  
E. R. Swenson ◽  
J. M. Hughes
Keyword(s):  
Metabolic Acidosis ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Respiratory Acidosis ◽  
Acute Effects ◽  
Acid Base Balance ◽  
Ventilatory Control ◽  
Peripheral Chemoreceptor ◽  
Ventilatory Responses ◽  
Base Balance

The effects of acetazolamide (ACTZ) on ventilatory control are thought to be mediated by metabolic acidosis. However, carbonic anhydrase (CA) inhibition within brain and chemoreceptors and tissue respiratory acidosis may also be important. We compared the acute effects of ACTZ (tissue respiratory acidosis and tissue CA inhibition without metabolic acidosis) on ventilation and ventilatory control with chronic ACTZ (acute effects plus metabolic acidosis). Five men were studied 1 h after 500 mg iv ACTZ or 0.9% saline (acute effects) and also after three doses of ACTZ (500 mg po every 6 h; chronic effects). Minute ventilation (VE), steady-state hypercapnic ventilatory response (HCVR), and hypoxic ventilatory response (HVR) were measured with respiratory inductance plethysmography. Resting VE was increased equally by acute and chronic ACTZ. HCVR increased with chronic ACTZ in hyperoxia and even further in hypoxia. In contrast, acute ACTZ had no effect on the HCVR slope in hyperoxia and suppressed its augmentation by hypoxia. HVR was fully suppressed by acute ACTZ but unchanged with chronic ACTZ. ACTZ also slowed the rate of full ventilatory response to CO2. These findings show that CA inhibitors affect ventilatory control in a complex fashion, not only through changes in systemic acid-base balance but also by central and peripheral chemoreceptor inhibition.

Practical Evaluation of Acid-Base Balance

1957 ◽  
Vol 3 (5) ◽  
pp. 631-637
Author(s):  
Herbert P Jacobi ◽  
Anthony J Barak ◽  
Meyer Beber
Keyword(s):  
Respiratory Acidosis ◽  
Respiratory Alkalosis ◽  
Acid Base Balance ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Plasma Bicarbonate ◽  
Practical Evaluation ◽  
Base Balance

Abstract The Co2 combining power bears a variable relationship to the in vivo plasma bicarbonate concentration, depending upon the type and severity of acid-base distortion. In respiratory alkalosis and metabolic acidosis the Co2 combining power will usually be greater than the in vivo plasma bicarbonate concentration; whereas, in respiratory acidosis and metabolic alkalosis the Co2 combining power will usually be less. Co2 content, on the other hand, will always parallel the in vivo plasma bicarbonate concentration quite closely, being only slightly greater. These facts, together with other considerations which are discussed, recommend the abandonment of the determination of CO2 combining power.

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