Ventilatory and blood acid-base adjustments to a decrease in body temperature from 30 to 10YC in black racer snakes Coluber constrictor

1996 ◽  
Vol 199 (4) ◽  
pp. 815-823
Author(s):  
J Stinner ◽  
M Grguric ◽  
S Beaty
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Minute Ventilation ◽  
Co2 Production ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Slow Increase ◽  
Coluber Constrictor ◽  
Steady State Levels ◽  
Time Required

There is increasing evidence that many amphibian and reptilian species use relatively slow ion-exchange mechanisms in addition to ventilation to adjust pH as body temperature changes. Large changes in blood bicarbonate concentration with changes in temperature have previously been reported for the snake Coluber constrictor. The purpose of the present study was to determine the ventilatory and pH adjustments associated with the increase in CO2 stores when the snakes are cooled. Body temperature was lowered from 30 to 10 °C within 4 h, at which time measurements of inspired minute ventilation (V.air), O2 consumption (VO2) and CO2 production (V.CO2) were started and continued for 56 h. The decrease in temperature produced a transient fall in the respiratory exchange ratio (V.CO2/VO2) to 0.2-0.3 and a steady-state value of 0.65±0.14 (mean ± s.d., N=7) was not achieved until about 35 h. There were concomitant transient reductions in V.air and V.air/V.O2. However, V.air/V.CO2 initially increased, with a corresponding reduction in arterial PCO2 (PaCO2) and increase in arterial pH. By 35 h, V.air/V.CO2 had decreased and PaCO2 had increased to steady-state levels, but pH decreased very little because of a gradual increase in bicarbonate concentration. We conclude that the drop in temperature imposed a metabolic acidosis for approximately 35 h because of the time required to increase bicarbonate concentration, and that the acidosis was compensated for by an elevated V.air/V.CO2. Steady-state breathing and acid-base status were not achieved until the relatively slow increase in CO2 stores had been completed.

Cardiovascular and metabolic responses to temperature in Coluber constrictor

1987 ◽  
Vol 253 (2) ◽  
pp. R222-R227 ◽  
Author(s):  
J. N. Stinner
Keyword(s):  
Blood Pressure ◽  
Body Temperature ◽  
Stroke Volume ◽  
Minute Ventilation ◽  
Marked Change ◽  
Effect Of Temperature ◽  
Metabolic Demand ◽  
Thermal Dependence ◽  
Arterial Blood ◽  
Coluber Constrictor

The cardiovascular adjustments associated with elevated metabolic demand caused by rising body temperature were investigated in Coluber constrictor. From 16 to 35 degrees C, O2 consumption increased roughly ninefold. Systemic blood flow, determined by the Fick method, increased approximately 4.5-fold and arteriovenous O2 difference increased approximately 2-fold. Heart rate steadily increased over the temperature range examined. At the cooler temperatures stroke volume also increased but, above approximately 25 degrees C, stroke volume declined with rising temperature. The changes in stroke volume may result from the direct effect of temperature on myocardial contractility. The thermal dependence of blood convection requirement in C. constrictor is similar to changes in air convection requirement determined in a previous study. Consequently the minute ventilation-to-perfusion ratio appears to be independent of temperature, at least from 20 to 35 degrees C. Systemic arterial blood pressure increases with rising body temperature due to the rise in cardiac output, whereas vascular resistance declines. Blood pressure in snakes disturbed by the investigator is roughly two times higher than in resting animals at all temperatures studied. This marked change in blood pressure suggests an "alarm reaction" mediated by the sympathetic nervous system.

Ventilation and CSF ions during hypocapnic HCl and HNO3 acidosis in conscious rabbits

1983 ◽  
Vol 55 (6) ◽  
pp. 1748-1757 ◽  
Author(s):  
E. E. Nattie ◽  
G. F. Birchard
Keyword(s):  
Minute Ventilation ◽  
Respiratory Frequency ◽  
Co2 Production ◽  
Central Venous ◽  
Acid Base ◽  
Arterial Pco2 ◽  
Mean Values ◽  
Frequency Responses ◽  
Ionic Mechanisms ◽  
Conscious Rabbits

In conscious rabbits with preimplanted arterial, central venous, and cisterna magna catheters, we infused HNO3 or HCl to lower and maintain arterial PCO2, pH, and plasma HCO-3 at the same mean values in both groups over 9 h. The hypothesis was that greater entry into cerebrospinal fluid (CSF) of the strong anion NO-3 vs. Cl- would result in a greater decrease in CSF [HCO-3] in the HNO3 vs. the HCl experiment, even though the acid-base stress as measured by arterial PCO2 and plasma [HCO-3] was the same. The results did not support the hypothesis. With HCl acidosis, delta CSF [HCO-3] was equal to delta CSF [Cl-]. With HNO3 acidosis, delta CSF [HCO-3] was equal to delta CSF [NO-3] + delta CSF [Cl-], as both CSF Cl- and HCO-3 decreased with NO-3 entry into CSF. The change in CSF [HCO-3] appeared tightly linked to the PCO2 or the plasma [HCO-3], it did not depend on the type of acid used. The ionic mechanisms that determine the CSF [HCO-3] in metabolic acidosis appear able to utilize changes in the strong anions NO-3 and Cl- to bring about CSF acid-base regulation. The change in alveolar ventilation per unit CO2 production as reflected by the arterial PCO2 was the same in both groups, although the expired minute ventilation and respiratory frequency responses were diminished in the HNO3 vs. the HCl groups. In both groups with acidosis, tidal volume increased, whereas respiratory frequency decreased.

Temperature Regulation and Heat Balance in Flying White-necked Ravens, Corvus Cryptoleucus

1981 ◽  
Vol 90 (1) ◽  
pp. 267-281 ◽  
Author(s):  
DENNIS M. HUDSON ◽  
MARVIN H. BERNSTEIN
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Wind Tunnel ◽  
Body Surface ◽  
Heat Balance ◽  
Metabolic Heat ◽  
Steady State Levels ◽  
Cutaneous Evaporation ◽  
Body Heat ◽  
Respiratory Evaporation

During level flight at 10 m.s−1 in a wind tunnel, white-necked ravens (Corvus cryptoleucus, mass 0·48 kg) exhibited an increase in body temperature to steady-state levels as high as 45°C, exceeding resting levels by nearly 3°C. This reflects the storage of up to half of the metabolic heat produced (Hp) during 5 min of flight. During steady-state flight, body heat was dissipated in part by respiratory evaporation and convection (13–40% of Hp) evoked by increases in ventilation proportional to body temperature. Remaining heat was lost by cutaneous evaporation (10% of Hp) as well as by radiation and convection from the external body surface. The results suggest strategies that might be used by ravens during flight under desert conditions.

Effect of ruminal CO2 on gas exchange and ventilation in the Hereford calf

1985 ◽  
Vol 58 (5) ◽  
pp. 1481-1484 ◽  
Author(s):  
W. D. Kuhlmann ◽  
S. R. Dolezal ◽  
M. R. Fedde
Keyword(s):  
Body Temperature ◽  
Gas Exchange ◽  
Respiratory Exchange Ratio ◽  
Minute Ventilation ◽  
Gas Absorption ◽  
Co2 Production ◽  
O2 Consumption ◽  
Ventilatory Pattern ◽  
Ruminal Epithelium ◽  
Expired Gas

The contribution of ruminal CO2 to gas exchange measurements and ventilation was determined in four rumen-fistulated Hereford steers at rest and during exercise. The calves were exercised at 1.4 and 2.2m X s-1 under three treatments: 1)full rumen with fistula sealed, 2) full rumen with fistula open, and 3) empty rumen. Measurements also were made at rest while flushing the empty rumen with either 100% N2 or a mixture of 50% CO2–50% N2. O2 consumption, CO2 production (Mco2), and ventilation were measured by collecting the expired gas. Absorption across the ruminal epithelium during rest increased Mco2 by 3%, whereas absorption and eructation together increased Mco2 by 15%. The respiratory exchange ratio (R) was significantly different among the three treatments at rest, but no differences were observed in R among the treatments during exercise. No changes were observed in minute ventilation among the three conditions, but a decrease in respiratory frequency and an increase in tidal volume occurred when the rumen was empty. These changes in ventilatory pattern may have been due to a decrease in body temperature when the rumen was empty. When the empty rumen was flushed with 50% CO2, Mco2 was increased 21% over the value observed when flushing with 100% N2. CO2 of fermentation origin is added to the expired gas by both eructation and absorption and has a significant effect on R in the resting animal, but no effect on R during exercise.

Temperature-induced changes in blood acid-base status in the alligator, Alligator mississipiensis

1978 ◽  
Vol 45 (6) ◽  
pp. 922-926 ◽  
Author(s):  
D. G. Davies
Keyword(s):  
Carbon Dioxide ◽  
Body Temperature ◽  
Minute Ventilation ◽  
Carbon Dioxide Production ◽  
Carbon Dioxide Partial Pressure ◽  
Acid Base ◽  
Arterial Blood ◽  
Acid Base Status ◽  
Body Temperature Increase ◽  
Alligator Mississipiensis

Gas exchange and arterial blood acid-base status were measured in 13 conscious alligators, Alligator mississipiensis, at 15, 25, and 35 degrees C. Arterial pH decreased by 0.250 units (from 7.635 to 7.385) and arterial carbon dioxide partial pressure increased by 11.4 Torr (from 11.8 to 23.2) as body temperature increased from 15 to 35 degrees C. No statistically significant changes occurred in arterial bicarbonate concentration. When OH-/H+ and alpha-imidazole were compared at each temperature, more variability was observed in OH-/H+, which increased from 8.7 to 12.0 as temperature increased from 15 to 35 degrees C. alpha-Imidazole remained essentially constant (0.76 at 15 degrees C and 0.80 at 35 degrees C). Body temperature increase caused marked increases in minute ventilation (VE), oxygen consumption (VO2), and carbon dioxide production (VCO2). The relative changes in these parameters resulted in a decrease in both VE/VO2 and VE/VCO2. The data of the present study are consistent with the concept that poikilotherms regulate their alveolar ventilation with changes in body temperature in order to keep OH-/H+ or alpha-imidazole constant.

Acid-base, metabolic, and ventilatory responses to repeated bouts of exercise

1982 ◽  
Vol 53 (2) ◽  
pp. 436-439 ◽  
Author(s):  
M. J. Buono ◽  
F. B. Roby
Keyword(s):  
Respiratory Exchange Ratio ◽  
Minute Ventilation ◽  
Co2 Flux ◽  
Cycle Ergometer ◽  
Mirror Image ◽  
Co2 Production ◽  
Acid Base ◽  
Subsequent Performance ◽  
Ventilatory Responses ◽  
Male Subjects

Acid-base, metabolic, and ventilatory responses to repeated bouts of exercise were examined. Ten male subjects performed two (T1, T2) 5-min work tests, on a cycle ergometer, separated by a 25-min rest. The results indicate the following. 1) T2 appears to have a larger aerobic energy component than T1, due to the fact that cumulative O2 uptake (Vo2) was significantly larger for T2 and that the immediate postexercise lactic acid (HLa) and delta HLa values were both significantly smaller for T2.2) CO2 production (Vco2) and the respiratory exchange ratio were both significantly lower for T2. This is probably due to greater fat metabolism and less nonmetabolic CO2 being produced from bicarbonate (HCO-3) buffering of HLa during T2.3) Even though Vco2 was significantly lower during T2, minute ventilation (VE) was not significantly different between T1 and T2. This suggests that the ventilatory response during exercise cannot be solely mediated via CO2 flux to the lungs. 4) HLa removal and (HCO-3) regeneration appear to be sequentially linked together as indicated by the almost identical mirror image and significant -0.93 correlation. In conclusion, it appears that a bout of high-intensity exercise (T1) can alter the acid-base and metabolic responses seen during subsequent performance (T2).

Effects of altered CSF [H+] on ventilatory responses to exercise in the awake goat

1988 ◽  
Vol 65 (2) ◽  
pp. 921-927 ◽  
Author(s):  
C. A. Smith ◽  
L. C. Jameson ◽  
J. A. Dempsey
Keyword(s):  
Steady State ◽  
Carotid Body ◽  
Ventilatory Response ◽  
Fold Increase ◽  
Co2 Production ◽  
Acid Base ◽  
Ventilatory Responses ◽  
Exercise Hyperpnea ◽  
Acid Base Status ◽  
Response To Exercise

We investigated the effects of selective large changes in the acid-base environment of medullary chemoreceptors on the control of exercise hyperpnea in unanesthetized goats. Four intact and two carotid body-denervated goats underwent cisternal perfusion with mock cerebrospinal fluid (CSF) of markedly varying [HCO-3] (CSF [H+] = 21-95 neq/l; pH 7.68-7.02) until a new steady state of alveolar hypo- or hyperventilation was reached [arterial PCO2 (PaCO2) = 31-54 Torr]. Perfusion continued as the goats completed two levels of steady-state treadmill walking [2 to 4-fold increase in CO2 production (VCO2)]. With normal acid-base status in CSF, goats usually hyperventilated slightly from rest through exercise (-3 Torr PaCO2, rest to VCO2 = 1.1 l/min). Changing CSF perfusate [H+] changed the level of resting PaCO2 (+6 and -4 Torr), but with few exceptions, the regulation of PaCO2 during exercise (delta PaCO2/delta VCO2) remained similar regardless of the new ventilatory steady state imposed by changing CSF [H+]. Thus the gain (slope) of the ventilatory response to exercise (ratio of change in alveolar ventilation to change in VCO2) must have increased approximately 15% with decreased resting PaCO2 (acidic CSF) and decreased approximately 9% with increased resting PaCO2 (alkaline CSF). A similar effect of CSF [H+] on resting PaCO2 and on delta PaCO2/VCO2 during exercise also occurred in two carotid body-denervated goats. Our results show that alteration of the gain of the ventilatory response to exercise occurs on acute alterations in resting PaCO2 set point (via changing CSF [H+]) and that the primary stimuli to exercise hyperpnea can operate independently of central or peripheral chemoreception.

scholarly journals Acid-Base Regulation and Ion Transfers in the Carp (Cyprinus Carpio) During and After Exposure to Environmental Hypercapnia

1984 ◽  
Vol 108 (1) ◽  
pp. 25-43 ◽  
Author(s):  
J. B. CLAIBORNE ◽  
NORBERT HEISLER
Keyword(s):  
Cyprinus Carpio ◽  
Environmental Water ◽  
Acid Base Balance ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Ph Adjustment ◽  
Carp Cyprinus Carpio ◽  
Net Uptake ◽  
Base Balance ◽  
Time Required

Acid-base balance and ion transfers were studied in the carp, Cyprinus carpio L., during and after 48 h of exposure to environmental hypercapnia (PCOCO27.5 Torr). Plasma pH, PCOCO2, [HCO3−], and net transfers of HCO3−, NH4+, Cl− and Na+ between the fish and the environmental water were measured periodically throughout the experiment. Over the first 8 h of hypercapnia, plasma PCOCO2 increased by 7.6 Torr with a concurrent decrease in plasma pH of 0.28 units. Plasma [HCO3−] was slowly elevated from about 14 to 22 mM after 48 h, at which point 50% of the pH depression expected at constant bicarbonate concentration had been compensated. The net amount of H+ transferred to the water was 3.3 mmol kg−1 fish, representing a 115% increase in the rate of cumulative H+ efflux, and inducing an elevation of both intracellular and extracellular [HCO3−]. Cl− transfer was reversed from a net uptake to a net efflux, while net Na+ influx was increased slightly. Following hypercapnia, plasma pH returned to control values within 1 h, while the plasma [HCO3−], which was elevated during hypercapnia, fell continuously to reattain pre-hypercapnic control values after 20 h. The [HCO3−] decrease was due to the net gain of H+ ions from the water during this period. Cl− transfer returned to a net uptake, while the original Na+ influx was reversed to a net loss. Acid-base regulatory responses in the carp are qualitatively similar to those observed in other fish, though the time required for compensatory pH adjustment is longer. It is concluded that alterations in the rates of Cl−/HCO3− and Na+/H+ exchanges during hypercapnia and Na+/H+ exchange following hypercapnia, play a significant role in the compensation of respiratory acid-base disturbances in these animals.

Continuous Estimation of CO2 Production during Exercise

1997 ◽  
Vol 36 (04/05) ◽  
pp. 368-371
Author(s):  
R. Soma ◽  
Y. Yamamoto
Keyword(s):  
Fuzzy Logic ◽  
Steady State ◽  
Infusion Rate ◽  
Feedback System ◽  
Whole Body ◽  
Co2 Production ◽  
Cycle Exercise ◽  
Continuous Estimation ◽  
Breath Measurement ◽  
13Co2 Enrichment

Abstract.A new method was developed for continuous isotopic estimation of human whole body CO2 rate of appearance (Ra) during non-steady state exercise. The technique consisted of a breath-by-breath measurement of 13CO2 enrichment (E) and a real-time fuzzy logic feedback system which controlled NaH13CO3 infusion rate to achieve an isotopic steady state. Ra was estimated from the isotope infusion rate and body 13CO2 enrichment which was equal to E at the isotopic steady state. During a non-steady state incremental cycle exercise (5 w/min or 10 w/min), NaH13CO3 infusion rate was successfully increased by the action of feedback controller so as to keep E constant.

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