C. Albers

Effect of acclimation temperature on intraerythrocytic acid-base balance and nucleoside triphosphates in the carp, cyprinus carpio

In carp acclimated to 20 degrees C or 10 degrees C intraerythrocytic pH (pHi) and plasma pH (pHe) were determined in vitro after equilibration with CO2 in either O2 or N2. ATP and GTP were determined with an enzymatic assay described in detail. The relationship between pHi, pHe and oxygen saturation was not affected by the acclimation temperature and was (pHi-6.10) = (0.853-0.159 X S) X (pHe-6.21) There was a slight but significant decrease in ATP at 20 degrees C. Apparent buffer values were affected by oxygenation and temperature. It is concluded from the recalculated CO2 Bohr factor and from the temperature effect on the buffer value that carp hemoglobin forms carbamate which decreases at a higher temperature. These changes in ATP and carbamate can partly account for the increase in whole blood oxygen affinity in carp acclimated at a high temperature.

Effect of acclimation temperature on oxygen transport in the blood of the carp, Cyprinus carpio.

The temperature dependence of the O2 equilibrium in whole blood was measured in carp acclimated for more than 3 weeks at 10 degrees C or 20 degrees C water temperature. O2 combining curves were obtained for the same samples at 10 degrees C or 20 degrees C using blood from the 10 degrees C or 20 degrees C acclimated fish (group A) or only at the acclimation temperature (group B). Whereas in group B the P50 was about the same at both temperatures, in group A P50 was higher at 20 degrees C than at 10 degrees C, yielding an apparent heat of oxygenation delta H = -9.9 kcal/mol at pH = 8.0. The CO2 Bohr effect in group A was delta log P50/delta pH = -0.93 at 20 degrees C and -1.17 at 10 degrees C, whereas in group B no temperature effect was seen (-0.98 and -0.97). The acclimation temperature had no effect on the electrophoretic Hb pattern. As expected, the in vivo pH changed inversely with temperature from 8.06 at 10 degrees C to 7.73 at 20 degrees C, enhancing the temperature-induced shift in P50. Acclimation reverses partly the changes in O2 affinity, thereby improving the uptake of oxygen in the gills.

Intracellular pH and buffer curves of cardiac muscle in rats as affected by temperature

Abstract To show the effect of temperature on the intracellular pH of cardiac muscle, pHi was obtained by simultaneous determination of 14C-labelled DM0 and 3H-labelled inulin. The experiments were performed in artificially ventilated male Sprague Dawley rats at a body temperature of 38.1 °C and of 21.5 °C. At Pco2 = 40 torr the following values were obtained at 38.1 °C (21.5 °C): pHa= 7.36 (7.36), pHi = 6.95 (7.9), calculated intracellular CO2 = 10.3 mM/kg H2O (21.5), calculated intracellular bicarbonate = 9.0 mM/kg H2O(19.54). For a constant CO2, content dpH/dT was − 0.0253 for the intracellular compartment, whereas for the extracellular compartment dpH/dT was −0.0127. The difference in dpH/dT between the intracellular and the extracellular compartments resembles the difference reported earlier between the mean whole body pHi and the arterial pH.

Oxygen transport and acid-base balance in the blood of the sheatfish, Silurus glanis☆

Oxygen binding and buffer properties of the blood of the sheatfish, Silurus glanis, were investigated in vitro at 20 and 10 degrees C. The O2 binding curves were hyperbolic with P50 = 10.1 mm Hg (20 degrees C, pH = 7.5) and 4.6 (10 degrees C, pH = 7.5). There was a very large Bohr effect with an average delta log P 50/delta pH of - 1.14. At 20 degrees C this value tended to be higher than at 10 degrees C. As a consequence the apparent heat of oxygenation depended on pH. The mean value of delta H was -10.4 kcal/mol. The Haldane effect was pronounced too (delta pH/delta S = -0.14) as was the Root effect. Isoelectric focussing revealed 3 major hemoglobin fractions with isoionic points in a more alkaline region than in carp hemoglobin. The non-bicarbonate buffer value was -10 mmol . 1-1. pH -1. The intraerythrocytic pH depended on the extracellular pH and the O2 saturation: pH = (0.87 - 0.14 S) (pHe -6.68 + 6.48). Delta pH/delta t for a constant CO2 content was -0.0166.

Intracellular pH in unanesthetized dogs during panting

Intracellular pH, arterial blood gases and several plasma enzymes were estimated in unanesthetized dogs during a 3-hour exposure to 30 degrees C/50% relative humidity, and 40 degrees C/50% relative humidity. No change occurred during mild heat stress, whereas during severe heat stress a profound respiratory alkalosis developed together with an increase in intracellular pH from 7.03 to 7.29. Most plasma enzymes increased by about 300% or more. In spite of extreme panting body temperature rose to 42.2 degrees C. Exposure to 40 degrees C/50% relative humidity with 4% CO2 in the climatic chamber inhibited the respiratory alkalosis and the increase of plasma enzymes. Though the panting frequency was lower the ventilatory heat dissipation was more efficient. Body temperature rose to only 39.8 degrees C. It is concluded that the intracellular buffering is not able to prevent marked changes of the intracellular pH during panting.

Indirect determination of mean whole body and intracellular CO2 and buffer capacity.

Abstract The DMO method was used to determine mean whole body intracellular pH i in artificially ventilated dogs at different arterial CO 2 tensions. The mean regression lines obtained were pH e = −0.669 log Pa CO 2 + 8.419 and pH i = −0.598 log Pa CO 2 + 7.923. Formulas are derived to convert these regression lines into CO 2 combining curves and buffer curves of the extracellular and the intracellular compartment. For Pa CO 2 = 40 torr the following values for the intracellular space were obtained: pH i = 6.965, HCO − 3 = 9.6 meq/kg H 2 O, total CO 2 = 10.9 mM/kg H 2 O, buffer capacity = 14.8 slyke/kg H 2 O. The corresponding values for the extracellular space were pH e = 7.347, HCO − 3 = 23.2 meq/kg H 2 O, total CO 2 = 24.5 mM/kg H 2 O and buffer capacity = 26.0 slyke/kg H 2 O. Total CO 2 and buffer capacity of the whole body was 8.6 mM/kg tissue and 10.7 slyke/kg tissue at Pa CO 2 = 40 torr. The intracellular space contributed 57% of these values. Position and slope of the calculated CO 2 combining curve agreed well with pertinent data of the literature based on direct tissue analysis, CO 2 elimination experiments or distribution kinetics of radioactive CO 2 .

Oxygen cost of panting in anaesthetized dogs

Abstract The oxygen cost of panting was assessed in 9 anaesthetized dogs by comparing the oxygen consumption during panting (9.32 ml · min− · kg−, rectal temperature tR = 41.1°C) with the values at a normal respiratory frequency (6.47 ml · min− · kg−, tR = 39.2°C) and immediately after the panting was stopped by suceinylcholine and replaced by artificial ventilation (7.64 ml · min−1 · kg−1, tR = 42.3°C). The effect of the rise in body temperature on VO2 was calculated to be 0.7 ml · min− · kg−1 between the control period and panting, the effect of the fall in PaCO2co during panting on VO2 was calculated to be 0.3 ml · min−1 · kg−1. Therefore from the 2.85 ml · min−1 · kg−1 difference between the control period and the panting period about one third could be explained by the rise in body temperature and the fall in PaCO2, whereas 1.8 ml · min− · kg− or two third were ascribed to the increased work of breathing during panting. The same estimate was obtained when the fall in VO2 after stopping the spontaneous ventilation during panting was used for the calculation. The overall cost of panting was calculated to be 1.2–1.6 ml of oxygen per liter total ventilation.

Effect of temperature on the intracellular CO2 dissociation curve and pH

Abstract Mean whole body pH i and pH e were determined at different arterial CO 2 tensions in two groups of dogs maintained at a body temperature of 41.6 and 27.1 °C. From the data HCO − 3 , total CO 2 and buffer capacity were calculated for the extracellular and intracellular fluid. The mean regression equations obtained for the hyperthermic group were pH e = −0.792 log Pa CO 2 + 8.531 and pH i = −0.759 log Pa CO 2 + 8.123. For the hypothermic group the following regression equations were obtained: pH e = −0.792 log Pa CO 2 + 8.610 and pH i = −0.759 log Pa CO 2 + 8.308. Total CO 2 and HCO − 3 were appreciably higher in the hypothermic group than in the hyperthermic group. The temperature effect was about 1 % CO 2 content at constant P CO 2 per °C for the ECF and 3 % CO 2 content at constant P CO 2 per °C for the ICF. At a constant CO 2 content ΔpH/Δt was −0.020 for the ECF and −0.037 for the ICF. It was shown that the effect of temperature on the relative alkalinity of the ICF expressed as the OH − /H + ratio would be minimal when the temperature change is done at a constant pH e rather than at a constant total CO 2 .

Effect of CO2 and lactic acid on intracellular pH of ascites tumor cells

The effect of CO2 and of lactic acid (L.A.) on the extracellular (pHe) and intracellular pH (pHi) of ascites tumor cells (DS-carcinosarcoma) in rats was studied by in vitro equilibration of ascites with CO2 and alteration of lactic acid concentration. pHi was determined by the distribution of DMO. The effects of lactic acid and CO2 on pH were additive and could be expressed as pHe = 8.872 - 0.745 logPCO2 - 0.0355 (L.A.) (R = 0.867, n = 201) pHi = 8.218 - 0.436 logPCO2 - 0.0275 (L.A.) (R = 0.812, n = 143) delta pHi/delta pHe was dependent on the way pHe was changed: If the change in pHe was due to lactic acid, delta pHi/delta pHe was 0.91; if it was due to CO2 delta pHi/delta pHe was 0.625. pHi exceeded pHe if either PCO2 and/or the concentration of lactic acid was raised above a critical level. The results render it questionable to predict intracellular pH values within solid tumor from pH measurements within the extracellular fluid.

H+ and Cl− ion equilibrium across the red cell membrane in the carp

H2O and electrolyte distribution were studied in carp erythrocytes at various pH values achieved by CO2/O2 equilibration in vitro. Intracellular pH was measured by means of glass electrode and by DMO-14C. rH+, rCl- and rDMO- varied linearly and in a comparable manner with pHe. At pHe = 7.8, rH+, rCl- and rDMO- were 0.21, 0.29 and 0.30. rCl- and rDMO- were closely correlated and exhibited only minor differences. rH+ was closely correlated with rCl- and rDMO-, but was, however, significantly lower than rCl- or rDMO-. This difference is considered to be due to a systematic error of the glass electrode when used in highly concentrated protein solutions. The coulometric determination of chloride in packed red cells is shown to be highly susceptible to protein. The results are consistent with the assumption that H+ and Cl- ions are passively distributed across the red cell membrane.