Respiration and circulation in an apodan amphibian

Toews, Daniel P.; Macintyre, Doug

doi:10.1139/z78-140

Cited by 38 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…pH/CO 2 levels (approximately 2·Pa) in burrowing cane toads whose nares were open to the air while the skin was surrounded by sand at 25°C for six·days (Boutilier et al, 1979b). Boutilier et al state that it is not uncommon for cane toads to encounter hypercapnic conditions in their environment (Boutilier et al, 1979a), including hypercapnic waters in the tropics (Toews and Macintyre, 1978). Investigations such as the current study offer insight into fundamental mechanisms of respiratory plasticity and may be of value in predicting how environmental changes such as increased atmospheric CO 2 may affect physiological function.…”

Section: Discussionmentioning

confidence: 73%

“…The respiratory physiology of this species has been well studied and these animals can encounter chronic hypercapnia in their natural environment (Boutilier et al, 1979a;Toews and Macintyre, 1978). In vitro brainstem-spinal cord preparations, in which vagal motor output was used as an index of breathing (fictive breathing), were used to assess respiratory-related central pH/CO 2 chemosensitivity.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Afferent input modulates the chronic hypercapnia-induced increase in respiratory-related central pH/CO2 chemosensitivity in the cane toad (Bufo marinus)

Gheshmy

Anari

Besada

et al. 2007

Journal of Experimental Biology

View full text Add to dashboard Cite

pH increased fictive breathing in preparations taken from control and CHC animals. CHC caused an increase in fictive breathing compared with controls. OD and CHH abolished the CHC-induced augmentation of fictive breathing. In vivo, CHC did not cause an augmentation of the acute hypercapnic ventilatory response. CHH reduced the in vivo acute hypercapnic ventilatory response compared with animals exposed to CHC. In vivo, OD reduced breathing frequency and increased breath amplitude in both control and CHC animals. The results suggest that afferent input from olfactory and arterial chemoreceptors, during CHC, is involved in triggering the CHC-induced increase in central respiratory-related pH/CO 2 chemosensitivity.

show abstract

Section: Discussionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Afferent input modulates the chronic hypercapnia-induced increase in respiratory-related central pH/CO2 chemosensitivity in the cane toad (Bufo marinus)

Gheshmy

Anari

Besada

et al. 2007

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…An obvious question is whether it contributes to separation of pulmonary and systemic venous blood streams. In Typhlonectes , which has a right atrial septum, Toews & MacIntyre () found that systemic arterial blood had a higher oxygen tension than pulmonary arterial blood showing some capacity for intracardiac blood stream separation. However, to our knowledge this is all that is known of intracardiac shunting in caecilians.…”

Section: Discussionmentioning

confidence: 99%

Extreme variation in the atrial septation of caecilians (Amphibia: Gymnophiona)

2014

View full text Add to dashboard Cite

Caecilians (order Gymnophiona) are elongate, limbless, snake-like amphibians that are the sister-group (closest relatives) of all other recent amphibians (frogs and salamanders). Little is known of their cardiovascular anatomy and physiology, but one nearly century old study suggests that Hypogeophis (family Indotyphlidae), commonly relied upon as a representative caecilian species, has atrial septation in the frontal plane and more than one septum. In contrast, in other vertebrates there generally is one atrial septum in the sagittal plane. We studied the adult heart of Idiocranium (also Indotyphlidae) using immunohistochemistry and confirm that the interatrial septum is close to the frontal plane. Additionally, a parallel right atrial septum divides three-fourths of the right atrial cavity of this species. Idiocranium embryos in the Hill collection reveal that atrial septation initiates in the sagittal plane as in other tetrapods. Late developmental stages, however, see a left-ward shift of visceral organs and a concordant rotation of the atria that reorients the atrial septa towards the frontal plane. The gross anatomies of species from six other caecilian families reveal that (i) the right atrial septum developed early in caecilian evolution (only absent in Rhinatrematidae) and that (ii) rotation of the atria evolved later and its degree varies between families. In most vertebrates a prominent atrial trabeculation associates with the sinuatrial valve, the so-called septum spurium, and the right atrial septum seems homologous to this trabeculation but much more developed. The right atrial septum does not appear to be a consequence of body elongation because it is absent in some caecilians and in snakes. The interatrial septum of caecilians shares multiple characters with the atrial septum of lungfishes, salamanders and the embryonic septum primum of amniotes. In conclusion, atrial septation in caecilians is based on evolutionarily conserved structures but possibly exhibits greater variation than in any other vertebrate order.

show abstract

“…Maina & Maloiy, 1988). However, in aquatic Typhlonectes compressicauda , as many as three lungs develop (Toews & MacIntyre, 1978). The lungs of caecilians are internally subdivided, forming air cells that are supported by diametrically placed trabeculae.…”

Section: Structure and Function Of Certain Gas Exchangersmentioning

confidence: 99%

Structure, function and evolution of the gas exchangers: comparative perspectives

2002

View full text Add to dashboard Cite

Over the evolutionary continuum, animals have faced similar fundamental challenges of acquiring molecular oxygen for aerobic metabolism. Under limitations and constraints imposed by factors such as phylogeny, behaviour, body size and environment, they have responded differently in founding optimal respiratory structures. A quintessence of the aphorism that 'necessity is the mother of invention', gas exchangers have been inaugurated through stiff cost-benefit analyses that have evoked transaction of trade-offs and compromises. Cogent structuralfunctional correlations occur in constructions of gas exchangers: within and between taxa, morphological complexity and respiratory efficiency increase with metabolic capacities and oxygen needs. Highly active, small endotherms have relatively better-refined gas exchangers compared with large, inactive ectotherms. Respiratory structures have developed from the plain cell membrane of the primeval prokaryotic unicells to complex multifunctional ones of the modern Metazoa. Regarding the respiratory medium used to extract oxygen from, animal life has had only two choices -water or air -within the biological range of temperature and pressure the only naturally occurring respirable fluids. In rarer cases, certain animals have adapted to using both media. Gills (evaginated gas exchangers) are the primordial respiratory organs: they are the archetypal water breathing organs.Lungs (invaginated gas exchangers) are the model air breathing organs. Bimodal (transitional) breathers occupy the water-air interface. Presentation and exposure of external (water/air) and internal (haemolymph/blood) respiratory media, features determined by geometric arrangement of the conduits, are important features for gas exchange efficiency: counter-current, cross-current, uniform pool and infinite pool designs have variably developed.

show abstract

Respiration and circulation in an apodan amphibian

Cited by 38 publications

References 12 publications

Afferent input modulates the chronic hypercapnia-induced increase in respiratory-related central pH/CO2 chemosensitivity in the cane toad (Bufo marinus)

Afferent input modulates the chronic hypercapnia-induced increase in respiratory-related central pH/CO2 chemosensitivity in the cane toad (Bufo marinus)

Extreme variation in the atrial septation of caecilians (Amphibia: Gymnophiona)

Structure, function and evolution of the gas exchangers: comparative perspectives

Contact Info

Product

Resources

About