Acute Temperature Change Research Articles

Thermal modulation of benzo[a]pyrene uptake in the gulf toadfish, Opsanus beta

AbstractGulf toadfish, Opsanus beta, were exposed to initial [14C]benzo[a]pyrene (BaP) concentrations of 5μg/L in a simple static system at high and low temperatures (18 or 28°C) following long‐term (>4 weeks) acclimation to these temperatures or an acute temperature change (18 to 28°C or 28 to 18°C) to assess the effects of temperature on the uptake and disposition of BaP. BaP uptake was estimated from the disappearance of BaP from the water. Uptake rates estimated at initial BaP concentrations for the four temperature treatments (acclimation temperature: exposure temperature), 28:18, 28:28, 18:18 and 18:28°C, were 0.020 ± 0.001, 0.051 ± 0.005, 0.031 ± 0.004 and 0.065 ± 0.004 μg BaP/g body weight/h (±se, N = 6). The decrease in BaP uptake with decreasing BaP concentration indicates that BaP uptake is directly proportional to the concentration in water, and calculated Q10 values suggest that uptake is modulated by temperature‐induced changes in respiration rate or convection volume. BaP was detected in all tissues examined, with the highest levels in the bile, the liver, the kidney and the gills. Greater uptake rates of carcinogens such as BaP at higher temperatures may in part explain higher rates of tumor formation in fish exposed to carcinogens at high temperatures.

Effects of Acute Temperature Change on Cardiac Performance and Oxygen Consumption of a Marine Fish, the Sea Raven (Hemitripterus americanus)

Sea ravens (Hemitripterus americanus), subjected to a temperature transition from 10° to 5° C over a 3-h period, showed a decrease in ventral aortic pressure from 42 to 18 cmH₂0 and a decrease in heart rate from 31 to 14 bpm. Isolated hearts, per-fused at 10° C with media containing 1 mM CaCl₂, were able to perform as well as in vivo hearts. When the in vitro preparation was taken from 10° to 5° C there was a small but significant decrease in performance and oxygen consumption over frequencies ranging from 12 to 48 bpm. The decrease in function in vivo was much more substantial than could be accounted for by the direct impact of temperature on the isolated heart. The small but significant decrease in performance by the isolated heart was not due to an impairment of energy-production mechanisms or limited extracellular calcium, as an increase in extracellular calcium resulted in an increase in oxygen consumption with no alteration in contractile performance.

The effects of temperature on metabolic rates of different life stages of Calanus glacialis in the Barents Sea

The effects of temperature on rates of respiration, excretion and gut evacuation were examined for copepodite stages and adult female Calanus glacialis collected in areas close to the ice-edge during the arctic summer in the Barents Sea. The various life history stages responded differently to acute temperature changes above the in situ temperature (ca.-1.7°C). Respiration rates of early copepodite stages (C I to C IV) were very variable whereas excretion rates declined with increasing temperature in the range from-1.7°C to +5°C. Rate of oxygen consumption of adult females were independent of temperature between-1.7° and +5°C, but increased as temperature increased from +5° to 10°C. Rates of excretion of copepodite stage V and adult females were independent of temperature in the range from-1.7° to +2°C, whereas excretion of copepodite stages III and IV was negatively related to temperature in the range from-1.7° to +5°C. In C IV, C V and adult females the instantaneous rate of gut evacuation increased with increasing temperature. The different response patterns of metabolic rates of small copepodite stages, copepodite stage V and adult females C. glacialis to acute temperature changes suggest that the capacity for adjustment of ammonia excretion is better developed in C V's and adult females than in the younger life stages.

Response of Sodium Flux in Goldfish to Acute Changes in Ambient Temperature

Response of Sodium Flux in Goldfish to Acute Changes in Ambient Temperature

Response of European flat oyster ( Ostrea edulis) hemocytes to acute salinity and temperature changes

European flat oysters, Ostrea edulis, were exposed in aquaria to an acute decrease in salinity or increase in temperature. Oysters were removed at timed intervals and hemolymph withdrawn by cardiac puncture. Hemocytes were measured in vitro for their ability to adhere fluorescent 2-μm latex microspheres (beads). Measurements were made with an epifluorescent microscope by counting the number of beads attached to the hemocytes, which were settled, fixed and stained on glass slides. Oysters maintained at 20°C and 30 ppt salinity were exposed to water at 15 ppt salinity. The ability of their hemocytes to adhere fluorescent beads decreased at 4 h and 8 h after immersion, but returned to control levels by 24 h. When temperature was increased to 25°C (30 ppt salinity), a similar pattern was found; a decrease in the ability to adhere beads at 4 h and 8 h, but a return to control levels by 24 h. Oysters maintained at 15°C then immersed in water at 20 and 25°C (30 ppt salinity) supported these results: bead adherence decreased after 6 h at the warmer temperatures, but was greater at 24 h and 72 h. These results indicate that acute temperature and salinity changes in oyster environments create changes in hemocyte activity and may be reflected by in vitro measurements of bead adherence.

Effect of Thermal Acclimation on Muscle Fiber Recruitment of Swimming Striped Bass (Morone saxatilis)

Recruitment pattern of red and white muscle fibers and initial swimming speeds of white muscle activation by thermally acclimated striped bass (Morone saxatilis) were determined by electromyography. Fish acclimated to 9 and 25 C were induced to swim in a stamina tunnel both at their respective acclimation temperatures and at a common temperature of 15 C. Speeds of initial white muscle recruitment (maximal sustainable swimming speed) are 1.95 ± 0.33 and 2.82 ± 0.26 BL s⁻¹ (body lengths s⁻¹) for animals swimming at their acclimation temperatures of 9 and 25 C, respectively. Thermal sensitivity of sustained swimming speed to acute temperature change is independent of the fish's thermal history, showing $Q_{10}'s$ of 1.47 and 1.53 for animals acclimated to 9 and 25 C, respectively. Cold acclimation of striped bass clearly leads to an increase in sustained swimming ability. When tested at 15 C, fish acclimated to 9 C are able to attain a speed of 2.46 ± 0.13 BL s⁻¹ using exclusively red muscle, while those acc...

Response of aquatic and aerial metabolic rates in the ribbed mussel Geukensia demissa (Dillwyn) to acute and prolonged changes in temperature

The effects of acute and prolonged changes in temperature on aerial and aquatic metabolic rates of Geukensia demissa (Dillwyn) were determined. Aquatic metabolic rate increased directly with acute changes in environmental temperature. Aerial metabolic rates exhibited a maximum at intermediate exposure temperature. The response of aerial metabolic rate to temperature indicates that at higher temperatures desiccation may be avoided at the expense of aerobic metabolism in air. Exposure to changes in temperature for ≈28 days resulted in complete acclimation of aerial metabolic rates and partial acclimation of aquatic rates. These results are consistent with the interpretation that partial acclimation of aquatic metabolic rate is due to acclimation of standard metabolic rates while components of metabolism associated with filtration activity did not acclimate.

Contractile responses to temperature in the locomotory musculature of striped bass Morone saxatilis

AbstractThe effects of temperature on contractile function of isolated, chemically skinned red (slow oxidative) and white (fast glycolytic) fibers of skeletal muscle from thermally acclimated striped bass (Morone saxatilis) were determined. Acclimation to 10° or 25°C has no significant effect on maximum isometric tension (Po) or maximum unloaded contraction velocity (Vo) of fibers of either muscle type. Sensitivity to acute changes in temperature is markedly greater for slow‐twitch fibers than for white, fast‐twitch fibers. Q10 (15–5°C) of Vo is 1.58 and 2.27 and R10 (15–5°C; analogous to Q10, but for parameters that are not rate functions) of Po is 1.57 and 2.17 for fibers from white and red muscle, respectively. R10 of maximum attainable power output is 1.29 for white and 4.50 for red fibers. Power for low speed, sustained swimming is derived exclusively from red muscle in striped bass, permitting comparisons between swimming performance and contractile capacity to be drawn. For maximum sustainable swimming speed at 15°C, calculated contraction velocity of a red muscle fiber corresponds to the maximum power output of a single fiber of red muscle at 15°C. Thermal sensitivity of red muscle power output predicts that maximum sustained swimming speed of striped bass will be severely impaired at cold temperatures. However, cold acclimation induces a proliferation of the red muscle mass that may ameliorate the thermal sensitivity of red muscle contractile function.

Biochemical responses to temperature in the contractile protein complex of striped bass Morone saxatilis.

The effects of acute and long-term changes in temperature upon catalytic and calcium regulatory function of red (slow oxidative) and white (fast glycolytic) muscle from striped bass (Morone saxatilis) were determined. Acclimation to 5 degrees C or 25 degrees C had no significant effect on catalytic function (ATPase activity) or regulatory sensitivity (Ca++-activation) of myofibrils from either muscle type. Substantial differences between red and white muscle were found in the intrinsic thermal sensitivity of maximally-activated Mg++-Ca++ myofibrillar ATPase. Arrhenius plots of myofibrillar ATPase from white muscle show one significant breakpoint at 29 degrees C, with activation energies (Ea) of 2.3 and 23.4 kcal mole-1 at temperatures above and below this transition, respectively. Arrhenius plots of myofibrillar ATPase from red muscle show two transitions occurring at 22 and 9 degrees C, with Ea of 7.6 kcal mole-1 above 22 degrees C and 18.3 kcal mole-1 between 9 and 22 degrees C. Activation energies for myofibrils from red muscle increase substantially to approximately 107.3 kcal mole-1 below the 9 degrees C breakpoint. Differences in the intrinsic thermal sensitivity of red and white muscle catalytic function are apparently due to interaction of actomyosins and calcium regulatory proteins which are specific to each muscle type. The results suggest that capacity for sustained swimming in striped bass, which is powered exclusively by red muscle, will be severely impaired at cold temperature unless compensations occur above the level of contractile proteins.

Thermoregulation in Bumblebee Colonies. I. Thermoregulatory versus Brood-Maintenance Behaviors during Acute Changes in Ambient Temperature

Colonies with 10–42 workers were subjected to ambient temperatures (Ta) of 3–38 C. Brood temperature (Tbr), the rate of oxygen consumption, the proportion of workers engaged in thermoregulatory behaviors (brood incubation and wing fanning), and the proportion of workers engaged in general brood maintenance were monitored. At Ta < 32 C Tbr was usually maintained at 28–32 C, and the percentage occurrence (incidence) of brood incubation varied inversely with Ta. At Ta > 32 C, wing fanning associated with a rise in Tbr and metabolism was prevalent. The incidence of brood maintenance was highest (40%–80%) at Ta = 25–32 C, when the combined incidence of brood incubation and wing fanning was relatively low. In contrast, the incidence of brood maintenance was <30% at near-freezing Ta and was 0%–10% at Ta > 34 C. These data suggest that the colonies attempt to regulate Tbr at a set-point temperature between 28 and 32 C and that the increased employment of workers for thermoregulation occurred at the expense of brood maintenance.

Interactive Effects of Acute Changes in Temperature and pH on Metabolism in Hepatocytes from the Sea Raven Hemitripterus americanus

Sea raven (Hemitripterus americanus) liver metabolism is similar to liver metabolism in other teleost fishes, with the following two notable exceptions: (1) lactate dehydrogenase levels and lactate utilization rates are extremely low, and (2) fatty-acid oxidation rates are much lower than those in other fish. The interaction of variations in temperature and extracellular pH on sea raven hepatocyte metabolism and intracellular pH were examined by measuring their effects on (1) both the rates of release of 14CO2 and production of 14C-glucose from labeled precursors (glucose, alanine, lactate, and oleate) and (2) the distribution ratios of 14C-5,5 dimethyloxazolidine-2,4dione (DMO). Temperature increases (from 10 to 18.5 C) resulted in increased metabolic rates (Q10 ≅ from 2 to 4). However, temperature decreases (from 10 to 2 C) led to marked deactivation of most pathways examined (Q10 ≅ from 5 to 20). Hexose monophosphate shunt activity was less temperature sensitive than glycolysis (as indicated by ratios of CO₂ release rates from C₁- vs. C₆-labeled glucose) and thus exhibited a relative increase in activity at 2 C. Temperature shifts produced small, transient changes in pHi (<0.15 units), which returned to control values by 1–2 h posttransfer. Decreases in pHe (0.4 units) had no significant effect on rates of CO₂ release and glucose production, and this appears to be due to the ability of the hepatocytes to rapidly return pHi to control values. These patterns of adjustment of pHi following temperature and extracellular pH changes observed in sea raven hepatocytes are different than those observed in other fish species (American eel and rainbow trout).

Thermal acclimation and oxygen consumption rates in neotenic grey-belly salamanders, Eurycea multiplicata griseogaster (plethodontidae), from an arkansas cave

1.1.|O2 consumption rates (V̇O2) in cave-dwelling neotenic grey-belly salamanders (Eurycea multiplica griseogaster) were measured at acclimation temperatures of 5, 10, 15 and 20°C, and acutely at ± 5°C, and compared with data reported for adults.2.2.|Inverse compensation (Precht Type V) was suggested at 5°C and partial acclimation (Precht Type III) between 15 and 20°C.3.3.|Neotenes showed no short-term compensation or metabolic insensitivity to acute ± 5°C changes.4.4.|Compared to epigean adults, neotenes had higher V̇O2 at all experimental temperatures.5.5.|Neotenes acclimated at 15°C and below were more sensitive to acute temperature changes within the 5–15°C range than adults. Those acclimated at 20°C were also more sensitive than adults to acute temperature changes above 15°C.6.6.|An opposite pattern of acute sensitivity occurred for 15°C-acclimated neotenes and adults in the 10–20°C and 15–25°C ranges.

Pain threshold changes induced by acute exposure to altered ambient temperatures

Our previous findings that the degree of endotoxin-induced hypotension in the dog is inversely related to ambient temperature (19° through 30°C) and that only increased doses of naloxone are effective at 19°C suggested that opioid activity is also influenced by ambient temperature, increasing in the cold and decreasing in the warm. Others have reported increases in plasma β-endorphin in rats with acute exposure to both 5° and 36°C. In this study we measured changes in pain thresholds after both acute and chronic exposures to lesser alterations in ambient temperature as a potentially more sensitive index of changes in central opioid activity. Compared to 24°C there was a marked increase in pain threshold with acute exposure to 10°C and marked decreases at 30° and 35°C. A slight decrease occurred after 30 minutes but not 60 or 120 minutes at 19°C. All acute changes disappeared three hours after the animals had been returned from the altered ambient temperature to 24°C. No changes were observed after six days chronic exposure to 10° or 30°C. These findings suggest that moderate, acute changes in ambient temperature can produce inversely related, adaptable alterations in central opioid activity.

Effects of acute stress, (1-24)ACTH administration and changes in superfusion temperature and flow rate on the in vitro secretion of glucocorticosteroids and aldosterone from the Mongolian gerbil (Meriones unguiculatus) adrenal gland.

The release of glucocorticosteroids and aldosterone rapidly decreased after start of superfusion and reached a steady base-line within 60-90 min of superfusion. While secretion markedly varied between experiments, it was very constant in the same experiment (coefficient of variation: 7.4-2.2% for glucocorticosteroids and 5.8-3.9% for aldosterone). After repeated exposure of adrenal tissue to 1 IU/ml (1-24)ACTH, glucocorticosteroid release progressively increased; under the same conditions aldosterone secretion was not changed. Glucocorticosteroid secretion from glands of animals stressed by 1-hr confinement or of animals injected with 6 IU (1-24)ACTH was significantly higher than that of controls over the 60-min superfusion period. Aldosterone secretion was not affected significantly by these pretreatments. After reduction of temperature from 35 to 1 degrees C, steroid release ceased. Elevation of temperature from 12 to 32 degrees C resulted in a linear increase of glucocorticosteroid and aldosterone secretion. A highly significant positive correlation was found between glucocorticosteroid and aldosterone amounts secreted from adrenals superfused at temperatures between 1 and 35 degrees C (r = 0.91, n = 116, P less than 0.0001). Changes of flow rate from 0.5 to 1.5 ml/min for 5 min induced a short term (1 min) stimulation of glucocorticosteroid and aldosterone release; reduction of flow rate to 0.5 ml/min for 5 min drastically diminished secretion of steroids below control levels for 1 min.

Stress‐induced water permeability changes in the tropical cichlid, Oreochromis niloticus (Trewavas)

The effect of short‐term, experimentally‐induced stress on the branchial water permeability of Oreochromis niloticus was studied. Both handling and thermal stress increased water permeability but apparently by different mechanisms. The enhancement of water permeability by acclimation temperatures and acute temperature changes had Q10 of 3.52 and 2.24 respectively. Environmental sodium concentration and acute hypoxia had no effect while hypercapnia and mild anaesthesia decreased water permeability. Both hypercapnia and mild anaesthesia probably elevated arterial pCO2 with a concomitant reduction of metabolism.

Muscle fiber activity in carp as a function of swimming speed and muscle temperature.

These experiments were performed to determine how ectothermal animals maintain their locomotory ability during acute changes in muscle temperature, despite the large thermal dependence of the mechanical properties of their muscle. The electrical activity of the red (slow-twitch) and white (fast-twitch) muscle fibers of carp was monitored while the carp swam at various speeds at 10 and 20 degrees C. The patterns of recruitment of different fiber types were similar at both temperatures. At low speeds only the red muscle was active, whereas at high speeds the white muscle was active as well. The swimming velocity at which white muscle was initially recruited increased from 26 cm/s at 10 degrees C to 46 cm/s at 20 degrees C. These results suggest that the order of recruitment of motor units was the same at 10 and 20 degrees C but that the recruitment occurred over a narrower range of speeds at the low temperature. Hence, to generate the muscle power required to swim at a certain velocity, fish recruit more muscle fibers, which include faster fiber types when their muscle is cold than when their muscle is warm.

Effects of acclimation temperature on routine metabolism muscle mitrochondrial volume density and capillary supply in the elver ( Anguilla anguilla L.)

1. 1.|Respiratory responses of juvenile European eel ( Anguilla anguilla L.) to acute and chronic temperature change have been investigated 2. 2.|Elvers were acclimated to either 10 or 29°C for 8 weeks thereafter standard O 2 consumption (V̇ o2) was 0.22 and 0.42 mg g −1 h −1, respectively. 3. 3.|Apparent Q 10 for routine O 2 consumption of acclimated elvers was 1.4. 4. 4.|Measurements of time-course of V̇ o2 changes during temperature acclimation suggest a partial compenation in metabolic rate. 5. 5.|Quantitative analysisof the fine structure and capillary supply to slow myotomal muscles was performed using electromicrograps. Volume densities of mitochondria were 0.26 for 10°C-acclimated elvers. In contrast, the surface and volume densities of capillaries (314 and 0.027 cm −1) were found to be independent of acclimation temperatures. 6. 6.|These results indicate that elvers are only capable of limited adjustments in metabolic rate, which may occount for their activity patterns at different temperatures.

Effects of acute changes in temperature and salinity on the oxygen uptake of larvae of herring (Clupea harengus) and plaice (Pleuronectes platessa)

Routine oxygen uptake (QO2) by yolk-sac and firstfeeding larvae of herring (Clupea harengus L.) and plaice (Pleuronectes platessa L.) was studied after acute change of temperature (8°, 13°, 18°C) and salinity (5, 12.7, 32, 40‰). In both species, QO2 (μl mg-1 dry wt h-1) of both larval stages increased with increasing temperature. Salinity effect on QO2 varied: for yolk-sac larvae of both species a lower QO2 was found at lower combined salinities (5 and 12.7‰); for feeding larvae a lower QO2 was observed at 12.7‰ for both species, possibly due to the relatively smaller size of larvae used at this salinity. For both species, oxygen uptake increased as larvae grew and weight regression coefficients were between 0.74 and 1.33. At 32‰ S, no difference was found in oxygen consumption between species as a function of temperature.

Intracellular pH-temperature interactions of hepatocytes from American eels.

The effects of acclimation temperature and acute temperature changes on the intracellular pH (pHi) of hepatocytes isolated from the American eel, Anguilla rostrata, were studied by the measurement of the distribution ratio of dimethyloxizolidinedione (DMO). Varying the concentration of DMO (10(-7) to 10(-4) M) did not affect estimates of pHi, indicating that DMO acts as an ideal pHi probe in eel hepatocytes. In vitro studies yielded values of liver cell pHi identical to those previously measured in vivo (in vitro pHi = 7.556 +/- 0.010; in vivo pHi = 7.570 +/- 0.049 at 20 degrees C); hepatocyte pHi varied inversely with acclimation temperature (5-20 degrees C) in a manner consistent with alphastat regulation (delta pH/delta T = -0.0182 +/- 0.021). During acute temperature increases (5-20 degrees C) and decreases (20-5 degrees C) hepatocytes regulated pHi to the appropriate (acclimated) value within 30-45 min posttransfer under conditions of constant medium pH (pHe). The effects of medium pH were also studied, and although patterns of pHi regulation differed between 5 and 20 degrees C cells, a pHi difference consistent with alphastat regulation was maintained between 5 and 20 degrees C cells over the pHe range 7.8-8.3.

Effects of Acute Temperature Changes on Metabolism, Heart Rate, and Ventilation Frequency in Carp Cyprinus carpio L.

Carp (Cyprinus carpio L.) were acclimated to 19.0 C and habituated to a metabolic chamber. At 19.0 C the metabolic rate was 27.1 ± 1.1 ml O2 · h−1 · kg−0.77, the heart rate 18.3 ± 0.34 beats · min−1, and the ventilation frequency 21.8 ± 0.90 ventilations · min−1 (means ± SEM). Rapid changes in ambient temperature (Ta) of 2.0, 4.0, 6.0, −2.0, −4.0, and −6.0 C elicited rapid temperature-dependent changes in metabolism and heart rate, both of which returned rapidly to the original value when the Ta was restored to 19.0 C. Ventilation frequency was altered significantly for the ± 4.0 and ± 6.0 C temperature displacements, whereas the ± 2.0 C changes produced consistent though not statistically significant alterations. Neither metabolic rate nor heart rate showed any major compensatory changes during the 60-min exposure to the altered Ta. Ventilation frequency responded immediately to the increased Ta, whereas there seemed to be a delay of up to 3.5 min before the heart rate increased. This dissociation of response of heart rate and ventilation was not observed when the Ta was lowered. The response of metabolic rate to the altered temperatures had a Q10 of 2.61, which is similar to Q10 values obtained for long-term acclimation. In calm carp, small or moderate acute shifts in body temperature produce metabolic changes which are comparable to those produced by long-term acclimation.