scholarly journals Ventilation and acid-base balance during graded activity in lizards

1981 ◽  
Vol 240 (1) ◽  
pp. R29-R37 ◽  
Author(s):  
G. S. Mitchell ◽  
T. T. Gleeson ◽  
A. F. Bennett
Keyword(s):  
Treadmill Exercise ◽  
Control Level ◽  
Hydrogen Ion ◽  
Co2 Production ◽  
Acid Base Balance ◽  
Acid Base ◽  
Lizard Species ◽  
Arterial Pco2 ◽  
Base Balance ◽  
Graded Activity

Arterial PCO2, hydrogen ion ([H+]a), and lactate ([L]a) concentrations, rates of metabolic CO2 production (VCO2) and O2 consumption (VO2), and effective alveolar ventilation (Veff) were determined in the lizards Varanus exanthematicus and Iguana iguana at rest and during steady-state treadmill exercise at 35 degrees C. In Varanus, VCO2 increased ninefold and VO2 sixfold without detectable rise in [L]a at running speeds below 1.0 to 1.5 km x h-1. In this range, Veff increased 12-fold resulting in decreased levels of PaCO2 and [H+]a. At higher speeds [L]a rose. Increments of 5 mM [L]a were accompanied by hyperventilation, reducing PaCO2 and thus maintaining [H+]a near its resting level. When [L]a increased further, [H+]a increased. Sustainable running speeds (0.3-0.5 km x h-1 and below) were often associated with increased VO2, VCO2, and [L]a in Iguana. Sixfold increases in VCO2 and 9-mM increments in [L]a were accompanied by sufficient increase in Veff (9-fold) to maintain [H+]a at or below its control level. When [L]a increased further, [H+]a increased. These results indicate that both lizard species maintain blood acid-base homeostasis rather effectively via ventilatory adjustments at moderate exercise intensities.

Impact of hydrogen ion on fasting ketogenesis: feedback regulation of acid production

1982 ◽  
Vol 242 (3) ◽  
pp. F238-F245 ◽  
Author(s):  
V. L. Hood ◽  
E. Danforth ◽  
E. S. Horton ◽  
R. L. Tannen
Keyword(s):  
Acid Production ◽  
Metabolic Regulation ◽  
Feedback Regulation ◽  
Hydrogen Ion ◽  
Acid Excretion ◽  
Acid Base Balance ◽  
Acid Base ◽  
Urine Ph ◽  
Ion Production ◽  
Base Balance

To determine whether acid-base balance regulates hydrogen ion production, seven obese volunteers were given NaHCO3 and NH4Cl (2 mmol.kg-1.day-1) during two separate 7-day fasts. On days 5-7 plasma bicarbonate was lower in the NH4Cl fasts (14.0 +/- 1.4 mM) than in the NaHCO3 fasts (18.3 +/- 1.1 mM), while urine pH and net acid excretion did not differ. Acid production (acid excretion minus intake) was greater by 204 mmol/day in the NaHCO3 fasts (274 +/- 16 mmol/day) than in the NH4Cl fasts (70 +/- 19 mmol/day). Ketoacid excretion, which reflected net ketoacid production, paralleled acid production, decreasing from 213 +/- 24 mmol/day in the NaHCO3 fasts to 67 +/- 18 mmol/day in the NH4Cl fasts. Thus, during starvation, alterations in hydrogen ion intake and the associated changes in acid-base balance modify the net production of endogenous acid by influencing the synthesis or utilization of ketoacids. Although the specific site of this metabolic regulation is undefined, these results indicate that systemic acid-base status can exert feedback control over hydrogen ion production.

Effect of potassium depletion on cerebrospinal fluid bicarbonate homeostasis

1976 ◽  
Vol 231 (2) ◽  
pp. 579-587 ◽  
Author(s):  
EE Nattie ◽  
SM Tenney
Keyword(s):  
Potassium Depletion ◽  
Acid Base Balance ◽  
Acid Base ◽  
Arterial Pco2 ◽  
Mixed Acid ◽  
Base Balance ◽  
Upward Direction ◽  
Relationship Of ◽  
The Relationship ◽  
K Depletion

We have examined the effect of K depletion on CSF [HCO3-] homeostasis in awake rats. The relationship of CSF [HCO3-] to arterial [HCO3-] in metabolic acid-base disturbances is displaced is an upward direction and has a significantly increased slope in K-depleted vs. control rats (0.51 +/- 0.02 vs. 0.42 +/- 0.02). Results of partial K-repletion experiments, with peripheral acid-base balance held constant, suggest that the effect is K specific. The K-depleted animals also exhibit a wider (CSF-arterial) PCO2 difference than controls (11.1 vs. 8.4 mmHg). When CSF [HCO3-] is shown as a function of CSF PCO2 the data of K-depleted rats are no longer displaced when compared to controls but still have a significantly greater slope (1.21 +/- 0.23 vs. 0.89 +/- 0.08). This increased slope is interpreted to reflect enhanced HCO3- movement from blood to CSF at high arterial [HCO3-]. Analysis of our data and observations from the literature in conditions of mixed acid-base disturbances suggest that CSF [HCO3-] is determined by a) CSF PCO2 and b) the level of arterial [HCO3-] when the latter is greater than the normal CSF [HCO3-].

scholarly journals The 100th anniversary of pH (1909-2009). Negative logarithms for measuring hydrogen ions: are they essential in medicine? Part I

2013 ◽  
pp. 147-155
Author(s):  
Francesco Sgambato ◽  
Sergio Prozzo ◽  
Ester Sgambato ◽  
Rosa Sgambato ◽  
Luca Milano
Keyword(s):  
Human Life ◽  
100Th Anniversary ◽  
Hydrogen Ion ◽  
Hydrogen Ions ◽  
Acid Base Balance ◽  
Acid Base ◽  
The Past ◽  
Scientific Papers ◽  
Base Balance ◽  
Ph Scale

Introduction: It has been 100 years since the concept of pH (1909-2009) was ‘‘invented’’ by the Danish chemist-mathematician Søren Peter Lauritz Sørensen (1868-1939) in the chemistry laboratories of the Carlsberg Brewery in Copenhagen. The anniversary provides an opportunity to examine the crucial importance in human life of acid-base balance. Materials and methods: The authors review the historical process that led to the creation of the pH scale, with citation of passages from the original work of Sørensen published 100 years ago. This is followed by a critical analysis of the debate regarding the use of logarithmstomeasure hydrogen ion concentrations based on data from scientific papers published over the past 50 years (1960-2010). Results and discussion: The authors conclude that the concept of acid-base balance can be approached and taught in a simpler, more exciting, and even pleasant fashion without using the infamous and abstruse Henderson-Hasselbalch equation. The whole rationale underlying the understanding and clinical application of this vital topic is clearly and unquestionably inherent simpler, more manageable formula introduced by Henderson (without logs), which is useful and quite adequate for use in medical education.

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)

Acid-base regulation during heating and cooling in the lizard, Varanus exanthematicus

1981 ◽  
Vol 50 (4) ◽  
pp. 779-783 ◽  
Author(s):  
S. C. Wood ◽  
K. Johansen ◽  
M. L. Glass ◽  
R. W. Hoyt
Keyword(s):  
Physiological Mechanism ◽  
Co2 Production ◽  
Acid Base Balance ◽  
Acid Base ◽  
Heating And Cooling ◽  
Arterial Blood ◽  
Arterial Ph ◽  
Base Balance ◽  
Response To Temperature ◽  
Induced Changes

Current concepts of acid-base balance in ectothermic animals require that arterial pH vary inversely with body temperature in order to maintain a constant OH-/H+ and constant net charge on proteins. The present study evaluates acid-base regulation in Varanus exanthematicus under various regimes of heating and cooling between 15 and 38 degrees C. Arterial blood was sampled during heating and cooling at various rates, using restrained and unrestrained animals with and without face masks. Arterial pH was found to have a small temperature dependence, i.e., pH = 7.66--0.005 (T). The slope (dpH/dT = -0.005), while significantly greater than zero (P less than 0.05), is much less than that required for a constant OH-/H+ or a constant imidazole alphastat (dpH/dT congruent to 0.018). The physiological mechanism that distinguishes this species from most other ectotherms is the presence of a ventilatory response to temperature-induced changes in CO2 production and O2 uptake, i.e., VE/VO2 is constant. This results in a constant O2 extraction and arterial saturation (approx. 90%), which is adaptive to the high aerobic requirements of this species.

Effect of body temperature on ventilatory control in the alligator

1982 ◽  
Vol 52 (1) ◽  
pp. 114-118 ◽  
Author(s):  
D. G. Davies ◽  
J. L. Thomas ◽  
E. N. Smith
Keyword(s):  
Body Temperature ◽  
Pulmonary Ventilation ◽  
Acid Base Balance ◽  
Acid Base ◽  
Arterial Pco2 ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Base Balance ◽  
Alligator Mississipiensis ◽  
Induced Changes

Pulmonary ventilation and arterial blood acid-base balance were measured in six unanesthetized alligators, Alligator mississipiensis, at 15, 25, and 35 degree C. The animals exhibited pronounced ventilatory responses to hypercapnia at all temperatures studied. Arterial PCO2 increased and pH decreased with increases in body temperature during both normocapnia and hypercapnia. The fractional dissociation of imidazole (alpha Pr) remained constant with changes in body temperature during normocapnia, but increased with temperature during hypercapnia. Ventilatory sensitivity, defined as delta (VE/VO2/delta (alpha Pr), was independent of body temperature. We conclude that the control of breathing in the alligator is a physiological defense of alpha Pr and that ventilatory responses occur following nontemperature-induced changes in blood acid-base balance, which tend to return alpha Pr to a normal value.

Effects of Diphosphonate and Colchicine Administration upon Acid–Base Changes Induced in Rats by Bilateral Nephrectomy

1979 ◽  
Vol 57 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Ailsa Goulding ◽  
M. F. Broom
Keyword(s):  
Skeletal Muscle ◽  
Hydrogen Ion ◽  
Bilateral Nephrectomy ◽  
Acid Base Balance ◽  
Acid Base ◽  
Ion Concentrations ◽  
Base Balance

1. The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) and colchicine on acid-base balance were examined in intact and nephrectomized rats. 2. Both drugs increased extracellular hydrogen ion concentrations and depressed extracellular bicarbonate concentrations in nephrectomized rats compared with controls but did not alter these parameters in intact animals. 3. Intracellular hydrogen ion concentrations in the skeletal muscle of nephrectomized rats given EHDP were higher than those of control animals. 4. It is postulated that colchicine and EHDP inhibit skeletal buffering of non-volatile acids produced endogenously in nephrectomized rats.

pH regulation of endogenous acid production in subjects with chronic ketoacidosis

1985 ◽  
Vol 249 (2) ◽  
pp. F220-F226 ◽  
Author(s):  
V. L. Hood
Keyword(s):  
Organic Acid ◽  
Acid Production ◽  
Ph Regulation ◽  
Acid Output ◽  
Hydrogen Ion ◽  
Significant Modification ◽  
Acid Base Balance ◽  
Acid Base ◽  
Effective Mechanism ◽  
Base Balance

In a previous study of starvation-induced acute ketoacidosis, net ketoacid production was inhibited by acid and facilitated by base ingestion. To determine whether hydrogen ion modifies net ketoacid production during chronic ketoacidosis, six over-weight volunteers ingested NaHCO3, NaCl, or NH4Cl (2 mmol X kg-1 X day-1), each for 7 days, during weeks 6-8 of ketogenic dieting. During days 4-7 of each phase, blood bicarbonate was stable but lower in the NH4Cl (19.6 +/- 0.7 mM) than the NaHCO3 (23.7 +/- 0.7 mM) phases. Throughout these periods, acid intake differed by 216 mmol/day, whereas acid output differed by 129 mmol/day between the NaHCO3 and the NH4Cl phases. The major contribution to this difference in acid balance was a difference in net organic acid (ketoacid) production. Although blood ketones were stable, ketoacid excretion, reflecting net ketoacid production, was decreased by 59% with acid and increased by 66% with base compared with NaCl (control) ingestion. Thus, in this state of chronic ketoacidosis, challenges to acid-base balance were countered by a rapidly occurring, sustained, reversible, and quantitatively significant modification of net acid production which acted as an effective mechanism for acid-base regulation.

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