Anaerobic contributions during progressive hypoxia in the toad Bufo marinus

D'eon, Michael E; Boutilier, Robert G.; Toews, Daniel P.

doi:10.1016/0300-9629(78)90028-2

Cited by 16 publications

(3 citation statements)

References 10 publications

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“…The sampled structure had a milky appearance that was consistent with earlier descriptions of the endolymphatic system. Both exercise and anoxia increased lactate concentrations in all tissues examined to levels observed in previous studies (Andersen and Wang, 2003;Armentrout and Rose, 1971;Bennett and Licht, 1974;D'Eon et al, 1978;Donohoe and Boutilier, 1999;Hutchison and Turney, 1975;Warburton et al, 1989;Wasser et al, 1993Wasser et al, , 1991Wegener and Krause, 1993). With the exception of gastrocnemius and heart, plasma had a higher lactate concentration than the other tissues examined, as has also been observed in cold hypoxic frogs (Donohoe and Boutilier, 1999) and cold anoxic turtles (Jackson et al, 1996).…”

Section: Bone Incubationssupporting

confidence: 48%

The role of mineralized tissue in the buffering of lactic acid during anoxia and exercise in the leopard frogRana pipiens

Warren

Jackson

2005

Journal of Experimental Biology

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SUMMARY To evaluate the role of mineralized tissues of the leopard frog in buffering acid, we analyzed the composition of femur and auditory capsule, the latter of which encloses a portion of the endolymphatic lime sacs, and investigated the extent to which these tissues are involved in buffering lactic acid after 2.5 h of anoxia and 10-19 min of strenuous exercise at 15°C. We analyzed the following tissues for lactate: plasma, heart, liver,gastrocnemius muscle, femur, auditory capsule and carcass. Plasma[Ca2+], [Mg2+], [inorganic phosphate (Pi)],[Na+] and [K+] were also measured. Femur Ca2+, Pi and CO32- compositions were similar to bone in other vertebrates. Auditory capsule had significantly more CaCO3 than femur. Lactate was significantly elevated in all tissues after anoxia and exercise, including femur and auditory capsule. Anoxia increased plasma [Ca2+], [Mg2+], [Pi]and [K+] and had no effect on plasma [Na+]. Exercise increased plasma [Mg2+], [Pi] and [K+] and had no effect on plasma [Ca2+] or [Na+]. The skeleton and endolymphatic lime sacs buffered 21% of the total lactate load during anoxia, and 9% after exercise. The exact contribution of the entire endolymphatic sac system to lactate buffering could not be determined in the present study. We conclude that the mineralized tissues function as buffers during anoxia and exercised induced lactic acidosis in amphibians.

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Section: Bone Incubationssupporting

confidence: 48%

The role of mineralized tissue in the buffering of lactic acid during anoxia and exercise in the leopard frogRana pipiens

Warren

Jackson

2005

Journal of Experimental Biology

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“…Blood lactate increases significantly in toads (Bufo marinus) when inspired P O ∑ drops below 10·mmHg (D'Eon et al, 1978) and in brain tissue of frogs (Rana temporaria) within 10·min exposure to anoxia (Wegner and Krause, 1993). This should cause a significant drop in brain tissue pH and potentially affect breathing.…”

Section: Discussionmentioning

confidence: 99%

Development of the respiratory response to hypoxia in the isolated brainstem of the bullfrogRana catesbeiana

Winmill

Chen

Hedrick

2005

Journal of Experimental Biology

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SUMMARY The aim of this study was to examine the effects of cellular hypoxia, and the contribution of anaerobic metabolism, on respiratory activity in bullfrogs at different stages of development. Respiratory-related neural activity was recorded from cranial nerve rootlets in isolated brainstem preparations from pre-metamorphic (Taylor–Köllros (T-K) stages VIII-XVI) and postmetamorphic tadpoles (T-K stages XXIV-XXV) and adults. Changes in fictive gill/lung activity in brainstems from pre-metamorphic tadpoles and lung activity in postmetamorphic tadpoles and adults were examined during superfusion with control (98% O2/2% CO2) or hypoxic (98%N2/2% CO2) artificial cerebrospinal fluid (aCSF). Iodoacetate (IAA; 100 μmol l–1) was used in conjunction with hypoxic aCSF to inhibit glycolysis. Gill burst frequency in pre-metamorphic brainstems did not change over a 3 h exposure to hypoxia and fictive lung burst frequency slowed significantly, but only after 3 h hypoxia. Blockade of glycolysis with IAA during hypoxia significantly reduced the time respiratory activity could be maintained in pre-metamorphic, but not in adult,brainstems. In brainstems from post-metamorphic tadpoles and adults, lung burst frequency became significantly more episodic within 5–15 min hypoxic exposure, but respiratory neural activity was subsequently abolished in every preparation. The cessation of fictive breathing was restored to control levels upon reoxygenation. Neither tadpole nor adult brainstems exhibited changes in neural bursts resembling `gasping' that is observed in mammalian brainstems exposed to severe hypoxia. There was also a significant increase in the frequency of `non-respiratory' bursts in hypoxic postmetamorphic and adult brainstems, but not in pre-metamorphic brainstems. These results indicate that pre-metamorphic tadpoles are capable of maintaining respiratory activity for 3 h or more during severe hypoxia and rely to a great extent upon anaerobic metabolism to maintain respiratory motor output. Upon metamorphosis, however, hypoxia results in significant changes in respiratory frequency and pattern, including increased lung burst episodes,non-ventilatory bursts and a reversible cessation of respiratory activity. Adults have little or no ability to maintain respiratory activity through glycolysis but, instead, stop respiratory activity until oxygen is available. This `switch' in the respiratory response to hypoxia coincides morphologically with the loss of gills and obligate air-breathing in the postmetamorphic frog. We hypothesize that the cessation of respiratory activity in post-metamorphic tadpoles and adults is an adaptive, energy-saving response to low oxygen.

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“…The effect of hypoxia on glucose levels was evaluated earlier in Bufo paracnemis (26) and Bufo marinus (27). Both studies reported a marked hypoxiainduced hyperglycemia at room temperature.…”

Section: Effect Of Temperature On Plasma Glucose Levelsmentioning

confidence: 99%

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana

Rocha¹,

Branco²

1997

Braz J Med Biol Res

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The objective of the present study was to determine the effects of hypoxia and temperature on the cardiovascular and respiratory systems and plasma glucose levels of the winter bullfrog Rana catesbeiana. Body temperature was maintained at 10, 15, 25 and 35 o C for measurements of breathing frequency, heart rate, arterial blood pressure, metabolic rate, plasma glucose levels, blood gases and acid-base status. Reducing body temperature from 35 to 10 o C decreased (P<0.001) heart rate (bpm) from 64.0 ± 3.1 (N = 5) to 12.5 ± 2.5 (N = 6) and blood pressure (mmHg) (P<0.05) from 41.9 ± 2.1 (N = 5) to 33.1 ± 2.1 (N = 6), whereas no significant changes were observed under hypoxia. Hypoxia-induced changes in breathing frequency and acid-base status were proportional to body temperature, being pronounced at 25 o C, less so at 15 o C, and absent at 10 o C. Hypoxia at 35 o C was lethal. Under normoxia, plasma glucose concentration (mg/dl) decreased (P<0.01) from 53.0 ± 3.4 (N = 6) to 35.9 ± 1.7 (N = 6) at body temperatures of 35 and 10 o C, respectively. Hypoxia had no significant effect on plasma glucose concentration at 10 and 15 o C, but at 25 o C there was a significant increase under conditions of 3% inspired O 2 . The arterial PO 2 and pH values were similar to those reported in previous studies on non-estivating Rana catesbeiana, but P a CO 2 (37.5 ± 1.9 mmHg, N = 5) was 3-fold higher, indicating increased plasma bicarbonate levels. The estivating bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures the sensitivity of most physiological systems to hypoxia is reduced.

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Anaerobic contributions during progressive hypoxia in the toad Bufo marinus

Cited by 16 publications

References 10 publications

The role of mineralized tissue in the buffering of lactic acid during anoxia and exercise in the leopard frogRana pipiens

The role of mineralized tissue in the buffering of lactic acid during anoxia and exercise in the leopard frogRana pipiens

Development of the respiratory response to hypoxia in the isolated brainstem of the bullfrogRana catesbeiana

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana

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