The influence of hypoxia on the blood regulation of the brackish water shrimp Palaemonetes varians Leach

During periods of hypoxia in hypotonic media, Palaemonetes varians Leach showed an unimpaired regulation of blood chloride until some minutes before death. Heart rate showed no clear dependence on the water oxygen tension (P_wO₂) and postbranchial haemolymph oxygen tensions slowly decreased during progressive hypopoxia from a normoxic level of ≈ 30 mm Hg until the animals turned opaque some minutes before they died. Blood pH increased in hypoxia, from 7.6 in normoxia to > 8 in P_wO₂ 10 mm Hg. Taken together, these data have been taken to indicate that the oxygen consumption rate at the critical point (MO₂ P_cr) of this species is very low (P_wO₂ = < 10 mm Hg) compared with other brackish water natantians studied. The ecological significance of this to the species is considered.     

Oxygen consumption and the respiratory responses to declining oxygen tension in the crab Ebalia tuberosa (Pennant) (Crustacea: Decapoda: Leucosiidae)

Oxygen consumption and its relationship to body weight and activity have been examined in Ebalia tuberosa (Pennant). Ebalia showed only very limited ability to regulate their oxygen consumption under conditions of declining P_O2. Respiratory independence was markedly affected by the level of activity of the animals. When inactive, respiratory independence was maintained down to a critical P_O2 of only about 130 mm Hg while when active, the crabs behaved as perfect conformers. Inactive Ebalia responded to a decrease in PO₂ by increasing the pumping activity of the scaphognathites and heart. This increased activity continued even at oxygen tensions lower than the P_c. The rate of reversals of the ventilatory currents did not change with decreasing P_O2. In the active crabs, the pumping activity of the scaphognathites and heart, and the rate of current reversals were higher than in the inactive animals, and a decrease in PO₂, did not bring about any further change in any of these responses. When exposed to hypoxic conditions for long periods initially inactive crabs survived longer than did active animals.     

Respiratory rate,haemolymph oxygen tension and haemocyanin level in the shrimp Palaemon adspersus: Rathke

The marine shrimp Palaemon adspersus Rathke, frequenting Zostera meadows, shows an oxygen consumption rate (MO₂) that is independent of water oxygen tension (P_wO₂) as PO₂ decreases to a critical point (P_cr) near 70 mm Hg. This respiratory independence is associated with maintenance of a relatively constant “arterial” (post-branchial) haemolymph tension (P_aO₂) at 70–80 mm Hg. At lower P_wO₂ values, both MO₂ and P_aO₂ fall, reflecting, in contrast to the above independence, a direct dependence of MO₂ on internal PO₂.Haemolymph copper measurements demonstrate relatively high haemocyanin concentrations and oxygen-carrying capacities, but MO₂ levels reflect an insignificant rôle for the pigment as an oxygen store.The data are discussed as regards adaptations for aerobic metabolism.     

Metabolic and ventilatory responses to hypoxia in two altitudinal populations of the toad, Bufo bankorensis

Effects of hypoxia on resting oxygen consumption ( ), lung ventilation, and heart rate at different ambient P_O2 were compared between lowland and high altitude populations of the toad, Bufo bankorensis. Resting decreased significantly in mild hypoxia (P_O2=120 mm Hg) at 10°C and in moderate hypoxia (P_O2=80 mm Hg) at 25°C in both altitudinal populations; however, resting did not differ significantly between the two populations. Numbers of lung ventilation periods (VP) and total inspired volume (V_L) did not change with P_O2 at 10°C, but did increase at moderate and severe hypoxia (40 mm Hg), respectively, at 25°C. Resting heart rates did not change during hypoxia and did not differ between altitude populations. The results suggest (1) the effect of P_O2 change on should be considered in future studies involving transfer of anurans to a different altitude; and (2) the metabolic and ventilatory physiology in B. bankorensis does not compensate for the low temperature and P_O2 at high altitude.     

Modulation of epithelial cell proliferation in culture by dissolved oxygen

Modulation of epithelial cell proliferation by the dissolved oxygen concentration (P_O2) of the growth medium was assessed with primary human foreskin epithelium and a continuous monkey kidney epithelial cell line (LLC-MK₂). Direct measurement of the growth medium P_O2 provides the first quantitative evaluation of epithelial cell proliferation as a function of P_O2 provides the first quantitative evaluation of epithelial cell proliferation as a function of P_O2. Sustained proliferation of LLC-MK₂ cells occurs in serum-free medium equilibrated with a gas phase containing 18% or 30% O₂ v/v. Mid-logarithmic phase cultures rapidly consume dissolved oxygen; this results in a 60–70 mm Hg decline in P_O2 and leads to a stable growth medium P_O2 between 70 and 100 mm Hg, well above anoxic values. In contrast, if culture medium is equilibrated with a gas phase containing 0% or 1% O₂ v/v to yield a growth medium P_O2 ～ 20–40 mm Hg, proliferation of LLC-MK₂ and primary foreskin epithelial cells is retarded, and LLC-MK₂ cells use little dissolved oxygen. Gentle, continuous rocking to prevent diffusion gradient formation enhances proliferation slightly at the higher P_O2, but neither periodic fluid renewals nor continued rocking stimulates cells retarded by a lowered oxygen concentration to resume proliferation. The data collectively demonstrate that epithelial cell proliferation requires a P_O2 > 40 mm Hg, and threshold requirements are probably closer to 70 mm Hg. Glycolysis continues at a P_O2 insufficient for proliferation, but more lactic acid accumulates in actively proliferating cultures than in cultures equilibrated with 0% oxygen. We conclude that epithelial cells in vitro both consume more oxygen and require a higher P_O2 for continued proliferation, and that the oxygen requirement for epithelial cell proliferation exceeds that of a comparable population of fibroblasts for which low oxygen may enhance survival and proliferation.     

The cardiac responses of the scallop Pecten maximus (L.) to respiratory stress

Heart activity of Pecten maximus (L.) has been recorded during various forms of experimentally induced respiratory stress. There was considerable variation in the responses of individual scallops but bradycardia generally occurred in response to all forms of respiratory stress, with the rate of fall in heart rate dependent upon the severity of hypoxia.When oxygen tension declined slowly in a closed respirometer there was regulation of both heart rate and oxygen consumption. The critical tension, P_c, for oxygen consumption lay between 70 and 80 mm Hg, and corresponded with a slight regulatory upswing of the heart rate, whereas the P_c for heart rate was much lower at 20–30 mm Hg. Sudden transfer to deoxygenated water for 3 h resulted in very rapid bradycardia and there was a rapid recovery and initial overshoot of the normal rate on return to well-oxygenated sea water. Aerial exposure for 3 h produced more gradual bradycardia followed by gradual recovery on return to sea water.The results of this work are compared in some detail with previous work on other species of bivalve from different geographical areas and habitats, and the mechanisms controlling cardiac and respiratory regulation are discussed. It is concluded that there are few clear-cut general differences between littoral and sublittoral species in their behavioural and physiological adaptations to hypoxia; the main distinguishing feature of littoral-adapted species is their ability to control air-gaping. Changes in heart activity generally indicate variations in metabolic rate, the speed at which the metabolic rate may be altered reflecting the degree of adaptation to the littoral environment.     

CEREBRAL BLOOD FLOW AND CEREBRAL METABOLIC RATES FOR OXYGEN, GLUCOSE, AND KETONE BODIES IN NEWBORN DOGS

Cerebral blood flow (CBF) and the cerebral metabolic rates for oxygen, glucose, acetoacetate, β-hydroxybutyrate and lactate were measured in 1- to 5-day old Beagle dogs under nitrous oxide anesthesia. CBF was determined by ¹³³Xe washout with mechanically integrated blood samples withdrawn simultaneously from a femoral artery and from the posterior one-third of the superior sagittal sinus. CBF and CMRO₂ in normocapnia (PaCO₂ 40 × 1 mm Hg) were 48 × 5 ml/100 g/min and 2.15 ml/100 g/min, respectively. There was a positive, linear relationship between CBF and PaCO₂, calculated for PaCO₂ values ranging from 26 to 70 mm Hg. Induced hypocapnia (PaCO₂ 31 × 1 mm Hg) or hypercapnia (PaCO₂ 58 × 2 mm Hg) did not alter the CMRO₂. Glucose and acetoacetate were taken up by the brain at all PaCO₂ levels examined; however, the cerebral uptake of glucose always exceeded the combined uptake of ketone bodies by more than a factor of ten. The cerebral metabolic rate for glucose (94.6 × 3.6 μmol/100 g/min) more than accounted for overall cerebral oxygen consumption, and yielded an oxygen:glucose ratio (mol:mol) of 5.1. Thus, as in adult animals, PaCO₂ is an important regulator of cerebral blood flow in puppies, and glucose is the major substrate for oxidative energy production in the immature brain. The oxidation of ketone bodies by the newborn dog brain accounts for not more than 6% of the in vivo cerebral oxygen consumption.     

Oxygen uptake of carp,Cyprinus carpio,swimming in normoxic and hypoxic water

Synopsis Oxygen uptake (V_{o 2}) was measured in carp of approximately 40 cm length swimming at controlled variable oxygen tensions (P_{o 2}). At P_{o 2}> 120 mm Hg V_{o 2} increased with an increase in swimming speed from 5.6 to 11.3 cm · sec^–1. Extrapolation of V_{o 2} to zero activity at P_{o 2} = 140 mm Hg revealed a standard O₂ uptake of 36.7 ml O₂ · kg^–1 · h^–1 at 20° C. At the lowest swimming speed (5.6 cm · s^–1) the oxygen uptake increased when the water P_{o 2} was reduced. A near doubling in V_{o 2} was seen at P_{o 2} = 70 mm Hg compared to 140 mm Hg. At higher swimming speeds in hypoxic water V_{o 2} decreased relative to the values at low swimming speeds. As a result the slope of the lines expressing log V_{o 2} as a function of swimming speed decreased from positive to negative values with decreasing P_{o 2} of the water. pH of blood from the caudal vein drawn before and at termination of swimming at P_{o 2} = 70 mm Hg and 100 mm Hg did not show any decrease in relation to rest values at P_{o 2} = 140 mm Hg. Blood lactate concentration did not increase during swimming at these tensions.     

The influence of dissolved oxygen concentration on phosphofructokinase and the glucose metabolism ofEscherichia coli K-12

The glucose metabolism and the response of phosphofructokinase activity to oxygen were investigated using glucose-limited chemostat cultures ofE. coli K-12. With a dilution rate of 0.2 hr^–1 and a glucose input concentration of 0.83 g/litre, 10 steady states were obtained ranging from 320 to 0 mm HgO₂. Dissolved oxygen reached zero level at a pO₂ of 25.8 mm Hg. The specific phosphofructokinase activity was constant above 28 mm Hg O₂ and increased linearly at lower pO₂ levels until it reached highest activity at 0 mm Hg O₂. Cell dry weight also started to decrease linearly from 28 to 5.9 mm Hg O₂, and fell sharply thereafter. Acid production rate did not start before pO₂ reached 25.6 mm Hg, increased progressively with an additional sharp increase below 5.9 mm Hg O₂. The main endproducts formed were acetic acid and ethanol with lactic acid appearing below 5.9 mm Hg O₂. The results suggest an effect of oxygen on phosphofructokinase synthesis rather than an ATP inhibition of the enzyme.This work was supported by a grant from the Australian Research Grant Commission.     

Serum-independent modulation of hemicyst formation by dissolved oxygen in postconfluent epithelial monolayers

Summary Hemicyst formation is considered a manifestation of either transepithelial solute and fluid movement or secretory activity in culture. This study shows that hemicyst formation in postconfluent monolayers of rhesus monkey kidney (LLC-MK₂) cells is modulated by the dissolved oxygen concentration (P_O2) of the culture medium. Either daily replacement of serum-free medium or displacement of the gas phase with 18% vol/vol O₂ (initial medium P_O2=125 to 135 mm Hg) enhances formation of hemicysts. Use of 30% O₂ (medium P_O2≊175 mm Hg) does not further increase the incidence, but neither 10% O₂ (medium P_O2=90 to 95 mm Hg) nor 1% O₂ (medium P_O2=35 to 50 mm Hg), the approximate range of dissolved oxygen values in blood, supports hemicyst formation unless cultures are gently rocked to disrupt diffusion gradients. Phase photomicrography of living cultures shows that the surface of a turgid hemicyst is furrowed, and cinephoto-micrography reveals that the walls vibrate subtly. When hypoxic conditions (0 to 1% O₂) are introduced this vibration ceases within 2 to 3 h, whereas collapse and disappearance of turgid hemicysts requires 18 to 20 h, seems virtually synchronous, and is reversible. Hemicysts form in a broad osmotic range, and increased electrolyte concentration increases the incidence. Hemicysts persist in localyy dense areas when cell-free strips are etched in the postconfluent monolayer; no DNA synthesis is detected under these conditions, but two-dimensional cell spreading into the denuded area is seen along the edge of the wound. We conclude that the dissolved oxygen supply in the cellular microenvironment modulates functional expression by differentiated kidney epithelial cells in culture and that increased electrolyte concentration also enhances expression of this phenotypic marker.     

The oxygen consumption of mayfly (Ephemeroptera) and stonefly (Plecoptera) larvae at different oxygen concentration

1. The aim of this investigation was to elucidate how four acquatic insect larvae, from different habitats and having different respiratory organs or types of respiratory regulation, react to a lowered oxygen concentration, and how their oxygen consumption is affected. The species investigated were the stoneflies Taeniopteryx nebulosa, Diura nanseni and Nemoura cincerea and the mayfly Cloëon dipterum.
2. The measurements were performed in a respiratory apparatus of open, flowing-water type. Its design is shown in Fig. 1. Water of known oxygen concentration was allowed to flow past the experimental larvae. The oxygen consumption of the larvae was calculated from the lowering of the oxygen concentration in which ensued.
3. The water used in the experiments was standardized, so that the electrode had the necessary stability (conductivity 470 micromhos/cm). The calcium ion was excluded in order to prevent the precipitation of CaCO₃ in the electrode capillary.
4. A large variation in the values of oxygen consumption was found as seen in Fig. 2–5. The reason for that is a corresponding variation in the motor activity of the experimental animals.
5. The physiological reasons for the general form of the curves A and C in Fig. 2–5 are discussed. The curves A and C represent oxygen consumption of the larvae at different degrees of stimulation, entailing different levels of motor activity. Curve A represents intentinally activated animals, curve C non-activated, motionless animals. The curves A and C are boundary curves corresponding to a sort of scope for activity of the animals. Over this scope area a series of curves of the same form could in principal be construed, representing different degrees of stimulation.
6. Within a certain oxygen concentration interval a motor activation was observed caused by a reduced oxygen concentration. The result of that activation can be seen in Fig. 2–5 as a zone with no or very few oxygen consumption values between curve C and D. The more easily activated the species is, the broader the zone will be. Cloën has the most narrow zone and was observed to be less activated than the other species.
7. Small larvae of Cloën (2–4 mm and 42–6 mm) and Nemoura (2–4 mm) showed clearly a greater ability to take up oxygen at low oxygen concentrations than full-grown larvae (see Fig. 8 and 9).
8. The critical point on the curve representing mean oxygen consumption as a function of oxygen concentrations was found to be at 2–5 mg O₂/1 for Taeniopteryx and Diura, at 2.2–2.5 mg O₂/1 for Cloëon, and at about 2–7 mg O₂/1 for Nemoura. The values refer to 8°. Cloëon is the species which is exposed to the greatest variations in oxygen concentration in its natural environment.
9. No influence on the oxygen consumption of starvation for 4 to 5 days was found. No difference between the oxygen consumption values obtained in the presence or in the absence of calcium ions could be observed during the experiments (Fig. 10, 11).
10. The basic picture obtained in this investigation is a set of oxygen consumption values scattered between a curve connecting highest values obtained and a curve of the standard metabolism together with a zone in which the larvae are activated by reduced oxygen concentrations. This picture is presumed to be general in aquatic animals with a well developed motor activity.

     

The influence of temperature on the haemocyanin function and oxygen uptake of the freshwater crab Potamonautes warreni calman

• 1.1. At 35°C a maximal VO₂ value of 110 ml O₂/kg/hr was obtained with a significant decrease in the value at 40°C.
• 2.2. The Bohr-effect for P. warreni is — 0.28 and does not change significantly at 15, 25 and 35°C.
• 3.3. The ability of the crab to extract oxygen from the water medium during a single exhalation is on average 41.2% whilst the limitation diffusion (L. diff, Piiper, [1982], A Companion to Animal Physiology, pp. 49–64. Cambridge University Press.) is 0.84.
• 4.4. Compared to land and marine crabs, in P. warreni, the P_aO₂ (29.5 mm Hg) and the P_vO₂ (15.3 mm Hg) is low.

     

ON THE RATE OF OXYGEN CONSUMPTION BY FERTILIZED AND UNFERTILIZED EGGS : IV. CHAETOPTERHS AND ARBACIA PUNCTULATA

1. Unfertilized eggs of Chaetopterus consume about 2.4 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. 2. In the 1st hour after fertilization, the fertilized eggs consume oxygen at about 53 or 54 per cent of this rate, which is about 1.3 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. 3. For the first 6 hours after fertilization, at 21°C., the curve of the rate of oxygen consumption is slightly asymmetrically sigmoid. The prefertilization rate is regained between 4½ and 5 hours after fertilization. Soon after 6 hours, ciliary activity begins, and the rate of oxygen consumption rises rapidly. 4. The unfertilized eggs of Arbacia punctulata consume about 0.36–0.5 mm.³ O₂ per hour per 10 mm.³ eggs at 21°C. The absolute determination is difficult as these eggs are highly sensitive to shaking in the manometer vessels, and these difficulties are discussed. 5. The fertilized eggs of Arbacia punctulata consume oxygen at the rate of about 2.0 mm.³ O₂ per hour per 10 mm.³ 21°C. At 1 hour after fertilization the rate is already rising. 6. A comparison of the absolute rates of oxygen consumption, and the changes in rate at fertilization of these and a number of other eggs, together with a theoretical discussion, and a discussion of discrepancies in measurements on the eggs of Arbacia punctulata, is contained in the fifth paper of this series (21).     

Metabolic oxygen conformity among lower vertebrates: The toadfish revisited

Summary The relationship between the ambient oxygen tension of the medium and the standard rate of oxygen consumption of toadfish (Opsanus tau) was reinvestigated. The toadfish, previously reported to be a metabolic oxygen conformer, actually is a metabolic oxygen regulator in a manner similar to most other fishes, with a critical oxygen tension (P _c) of 29.3±3.5 mm Hg at 22 °C. This contradiction of a classical example of O₂ conformity in a lower vertebrate, when considered with other conflicting evidence for O₂ conformity among lower vertebrates, suggests that the concept that there are lower vertebrates that routinely exhibit metabolic O₂ conformity may be questionable, especially for forms with no obvious limitation of O₂ transport mechanisms.     

Respiration and oxygen transport functions of the blood from an intertidal fish,Helcogramma medium (Tripterygiidae)

Synopsis Aquatic and aerial oxygen uptake (̇O₂), ventilation frequency, and oxygen transport properties of the blood were determined for the intertidal fish Helcogramma medium. Ventilation frequency increased in response to decreased environmental PO₂ and aquatic ̇O₂ was maintained down to a critical PO₂ of 30–40 mm Hg. Below PO₂ 30 mm Hg fish intermittently gulped air and finally emerged into air at PO₂ 18 mm Hg. After 1 h exposure to air ̇O₂ decreased to 60% of the aquatic rate and this was accompanied by an increase in blood lactate. Aerobic expansibility was reduced in air (×1.2) compared to water (× 5.5). The Hb concentration was 0.47 ± 0.13 mmol 1^–1 and hematocrit 11.55 ± 3.61% indicating a moderate O₂-carrying capacity. Oxygen affinity was not especially high (P₅₀ = 19 mm Hg at pH 7.7 and 15°C) and ATP was the predominant acid-soluble phosphate regulating P₅₀. The equilibrium curve was essentially hyperbolic (Hill's n = 1.2) with a marked Bohr effect = –1.06) and Root effect (saturation depressed by 50% at pH7.1). The pattern of respiration and the respiratory properties of the blood together with observations of the behaviour of the fish during aerial exposure indicated that Helcogramma is adapted to living in a well-aerated environment yet can adequately tolerate short term exposure to low aquatic PO₂ or air.     

Effects of inhalational anesthesia on blood gases and pH in California sea lions

Despite the widespread use of inhalational anesthesia with spontaneous ventilation in many studies of otariid pinnipeds, the effects and risks of anesthetic‐induced respiratory depression on blood gas and pH regulation are unknown in these animals. During such anesthesia in California sea lions (Zalophus californianus), blood gas and pH analyses of opportunistic blood samples revealed routine hypercarbia (highest P_CO2 = 128 mm Hg [17.1 kPa]), but adequate arterial oxygenation (P_O2 > 100 mm Hg [13.3 kPa] on 100% inspiratory oxygen). Respiratory acidosis (lowest pH = 7.05) was limited by the increased buffering capacity of sea lion blood. A markedly widened alveolar‐to‐arterial P_O2 difference was indicative of atelectasis and ventilation‐perfusion mismatch in the lung secondary to hypoventilation during anesthesia. Despite the generally safe track record of this anesthetic regimen in the past, these findings demonstrate the value of high inspiratory O₂ concentrations and the necessity of constant vigilance and caution. In order to avoid hypoxemia, we emphasize the importance of late extubation or at least maintenance of mask ventilation on O₂ until anesthetic‐induced respiratory depression is resolved. In this regard, whether for planned or emergency application, we also describe a simple, easily employed intubation technique with the Casper “zalophoscope” for sea lions.     

Der Einfluß des Sauerstoffpartialdruckes und der Antibiotica Actinomycin und Puromycin auf das Wachstum,die Synthese von Bacteriochlorophyll und die Thylakoidmorphogenese in Dunkelkulturen von Rhodospirillum rubrum

Zusammenfassung Die Wachstumsrate (1/p; p = Proteinverdopplungszeit) von Rhodospirillum rubrum in aeroben Dunkelkulturen ist vom Sauerstoffpartialdruck abhängig. Das Optimum liegt bei 3–5 mm Hg [O₂]. Steigt die O₂-Konzentration auf 150 mm Hg [O₂] an, so vermindert sich die Wachstumsrate langsam um etwa 10%. Unterhalb 2 mm Hg fällt sie dagegen steil nach 0 ab. Die Ausbildung des gesamten Systems der Photophosphorylierung (Thylakoide, Chromatophoren) ist ein lichtunabhängiger, aber vom Sauerstoffpartialdruck direkt abhängiger Prozeß. Die Morphogenese wird induziert, wenn der Sauerstoffpartialdruck auf etwa 20 mm Hg erniedrigt wird. Das Optimum der Bacteriochlorophyll-bildung unter aeroben Dunkelbedingungen liegt bei etwa 2 mm Hg [O₂]. Die Pigmentsynthese kann durch Veränderung der Sauerstoffkonzentration induziert werden, ohne die Wachstumsgeschwindigkeit in der logarithmischen Wachstumsphase zu verändern. Eine Änderung der Wachstumsrate führt zu einer relativen Verschiebung der Syntheseraten für DNS, RNS und Protein.

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Summary The growth rate (1/p; p = time for protein doubling) of Rhodospirillum rubrum in aerobic dark cultures is dependent from the oxygen partial pressure. The optimum of growth is achieved at an oxygen partial pressure of 3 to 5 mm Hg. At 150 mm Hg [O₂] the growth rate will be reduced to 90% of the optimal rate. After lowering the oxygen partial pressure below 2 mm Hg the growth rate is dropped very strongly.The morphogenesis of the thylakoid-or chromatophore—membranes and the biosynthesis of bacteriochlorophyll are light independent processes. The morphogenesis is started by lowering the oxygen partial pressure. The optimum of bacteriochlorophyll synthesis in dark cultures is near the oxygen concentration of 2 mm Hg. It is possible to induce the pigment synthesis by lowering the oxygen partial pressure without changing the growth rate. But a change of the growth rate implies a change of the quotient protein/RNS and RNS/DNS. After induction of bacteriochorophyll synthesis early proteins are synthesized which are needed for the last part of the Mg-way of tetrapyrrol synthesis.

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Im Text verwendete Abkürzungen B.-Chlorophyll Bacteriochlorophyll - DNS Desoxyribonucleinsäure - RNS Ribonucleinsäure - ATP Adenosintriphosphat     

Respiratory characteristics of the blood pigments of three worms from an intertidal mudflat

Abstract

Three worms living in an intertidal mudflat near Auckland have respiratory pigments with different oxygen-binding properties. The burrowing sipunculid Xenosiphon mundanus has hemerythrin contained within coelomic cells. Oxygen is co-operatively bound to the hemerythrin (Hill's coefficient, n, = 1.8), resulting in a sigmoidal oxygen-binding curve of high oxygen affinity (halfsaturation tension, P₅₀, = 7.0 mm Hg at pH 7.5 and 20°C). Oxygen release is regulated by pH, and the Bohr effect is quantified by Ф = Δ log P₅₀ / ΔpH = - 0.30. The errant polychaete Glycera sp. has hemoglobin-charged coelomocytes with low oxygen affinity (P₅₀ = 13.5 mm Hg at pH 7.3 and 20°C)? and the oxygen-binding curve is essentially hyperbolic and insensitive to pH. The burrowing polychaete Abarenicola affinis has a vascular (circulating) erythrocruorin which binds and releases much oxygen for small changes in PO₂ (Hill's n = 3.8) and is insensitive to pH (Ф = -0.09). The physiological properties of these pigments cannot be related to the availability of oxygen in the near-environment, or to the habits of the animals, but appear to be dictated by the level of body organisation, particularly with regard to the gas exchange surfaces.     

Temperaturadaptation der Sauerstoffaffinität des Blutes von Rana esculenta L.

Zusammenfassung Die Sauerstoffaffinität des Blutes (ausgedrückt im Sauerstoffhalbsättigungsdruck P ₅₀) von an 5° C adaptierten Fröschen (Rana esculenta L.) ist bei gleicher Umgebungstemperatur geringer als bei an 20° C adaptierten Fröschen. P ₅₀ bei pH 7,4 und 20° C Umgebungstemperatur betrug 42,4 mm Hg bei den kälte- und 39,1 mm Hg bei den wäremadaptierten Fröschen (Abb. 1). Die Sauerstoffkapazität der kälteangepaßten Frösche von 12,33 ml O₂/100 ml Blut ist höher als die der wärmeangepaßten von 10,43 ml O₂/100 ml Blut (Tabelle 1). Die Bedeutung und die Ursache der Sauerstoffkapazitäts- und Sauerstoffaffinitätsadaptation im Hinblick auf die Stoffwechseladaptation werden diskutiert.

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Temperature adaptation of the oxygen affinity of the blood in Rana esculenta L.

Summary The oxygen affinity of blood (expressed by the oxygen half saturation pressure P ₅₀) in frogs (Rana esculenta L.), adapted to 5° C is less as in frogs, adapted to 20° C at equal experimental temperature. P ₅₀ in cold-adapted frogs related to pH 7.4 and 20° C is 42.4 mm Hg and in heat-adapted frogs 39.1 mm Hg (Fig. 1). The oxygen capacity of the cold-adapted frogs is with 12.33 ml O₂/100 ml blood higher than of the heat-adapted frogs with 10.43 ml O₂/100 ml blood (Table 1). The importance and the origin of the adaptation of the oxygen affinity and capacity in view to the adaptation of the metabolic rate are discussed.

     

Atmospheric stability in cell culture vessels

Summary We have investigated the atmospheric stability in polystyrene and glass cell culture vessels by measuring the dissolved O₂ and CO₂ in the media of both seeded and unseeded culture vessels incubated at 37°C. There was no diffusion of either O₂ or CO₂ through glass vessels. At low partial pressures of oxygen (P_{O 2}), oxygen diffused into the polystyrene flasks at a rate of 1 to 2 mm Hg per 24 hr, and at high P_{O 2}, oxygen diffused slowly out of polystyrene flasks. CO₂ diffused out of polystyrene flasks with a half-time of 260 hr resulting in a considerable elevation in pH. In seeded polystyrene flasks with the P_{O 2} ⩽ room air, cellular oxygen consumption was masked by the inward diffusion of oxygen. In addition, the fall in pH due to metabolic CO₂ and organic acid production during cell growth in polystyrene flasks was buffered by the diffusion of CO₂ out of the vessels. Presented, in part, by Dr. Arthur Balin in partial fulfillment of the requirements for the Ph.D. This work was supported by USPHS grants AG-00378 from the National Institute of Aging and CA-14345 from the National Cancer Institute and NR 202-005 from the Office of Naval Research. A.K.B. is a trainee of the Medical Scientist Training Program, National Institutes of Health (GM 02046).