Resting respiratory behavior in minimally instrumented toads - effects of very long apneas on blood gases and pH

Coelho, Flávio Codeço; Smatresk, Neal J.

doi:10.1590/s1519-69842003000100006

Cited by 14 publications

(9 citation statements)

References 20 publications

(12 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, lung ventilation episodes occur in bullfrogs despite unidirectional ventilation that eliminates oscillations in blood gases (Kinkead and Milsom, 1994). In addition, minimally instrumented Bufo (=Chaunus) marinus exhibit very long apneas (up to 8·h) despite very low arterial P O 2 and stable arterial P CO 2 levels (Coelho and Smatresk, 2003). We have shown that a number of skeletal muscles compress lymph sacs in the posterior region of anurans to move lymph dorsally (Drewes et al, 2007).…”

Section: Discussionmentioning

confidence: 86%

See 1 more Smart Citation

Lung ventilation contributes to vertical lymph movement in anurans

Hedrick

Drewes

Hillman

et al. 2007

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY Anurans (frogs and toads) generate lymphatic fluid at 10 times the rate in mammals, largely as a consequence of their very `leaky' vasculature and high interstitial compliance. Lymph is ultimately pumped into the venous system by paired, dorsally located lymph hearts. At present, it is unclear how lymphatic fluid that accumulates in central body subcutaneous lymph sacs is moved to the anterior and posterior lymph hearts in the axillary regions and how lymph is moved, against gravity, to the dorsally located lymph hearts. In this study,we tested the hypothesis that lung ventilation, through its consequent effects on lymph sac pressure, contributes to the vertical movement of lymphatic fluid in the cane toad (Chaunus marinus) and the North American bullfrog(Lithobates catesbeiana). We measured pressure in the dorsal, lateral and subvertebral lymph sacs of anesthetized cane toads and bullfrogs during artificial lung inflation and deflation. We also measured pressure in the subvertebral lymph sac, which adheres to the dorsal surface of the lungs,simultaneously with brachial (forelimb) and pubic (posterior) sac pressure during ventilation in freely behaving animals. There were highly significant(P<0.001) relationships between lung pressure and lymph sac pressures (r2=0.19–0.72), indicating that pulmonary pressure is transmitted to the highly compliant lymph sacs that surround the lungs. Subvertebral sac pressure of resting animals was not significantly different between L. catesbeiana (518±282 Pa) and C. marinus (459±111 Pa). Brachial sac compliance (ml kPa–1 kg–1) also did not differ between the two species (33.6±5.0 in L. catesbeiana and 37.0±9.4 in C. marinus). During expiration (lung deflation), reductions in expanding subvertebral sac pressure are communicated to the brachial lymph sac. Changes in brachial and pubic lymph sac pressures were correlated almost entirely during expiration rather than inspiration. The change in brachial sac pressure during expiration was 235±43 Pa for C. marinus and 215±50 Pa for L. catesbeiana, which is of sufficient magnitude to move lymph the estimated 0.5–1.0 cm vertical distance from the forelimb to the vicinity of the anterior lymph hearts. We suggest that lymph is moved during expiration to the subvertebral sac from anterior and posterior lymph sacs. During lung inflation, increased lymph sac pressure moves lymph to axillary regions, where lymph hearts can return lymph to the vascular space. Consequently, pulmonary ventilation has an important role for lymph movement and, hence, blood volume regulation in anurans.

show abstract

Section: Discussionmentioning

confidence: 86%

“…Anurans (frogs and toads) are an enigma from a respiratory perspective because their ventilation is only loosely coupled to blood oxygen partial pressure (P O 2) and carbon dioxide partial pressure (P CO 2) (Coelho and Smatresk, 2003;Gargaglioni and Milsom, 2007) whereas in other vertebrate classes it is tightly coupled.…”

Section: Introductionmentioning

confidence: 99%

Lung ventilation contributes to vertical lymph movement in anurans

Hedrick

Drewes

Hillman

et al. 2007

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Because amphibians use multiple methods for respiratory exchange (pulmonary, buccopharyngeal, and cutaneous), apnea is less of a concern than in other vertebrate groups, although hypoxia and respiratory acidosis have been reported in several amphibian species (including Bufo toads) during periods of apnea (Wright, 2001;Andersen and Wang, 2002;Coelho and Smatresk, 2003). Amphibians are thought to be more tolerant of hypoxia and associated metabolic disturbances than are mammals because of adaptations for aestivation and dormancy in some species (Bickler and Buck, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Despite the wide use of animals in this genus, there are few published studies evaluating the effects of anesthesia in Bufo toads. The available studies often focus on specific physiologic changes in a research setting and are not clinical anesthetic trials or comparisons (Middler et al, 1968;Smith, 1974;Stetter et al, 1996;Andersen and Wang, 2002;Coelho and Smatresk, 2003). Extrapolation from anesthetic trials in other anuran species may not be accurate because the majority of studies have been performed with immersion or topical anesthetics using aquatic anurans, which have thinner skin that is potentially more permeable to anesthetic agents (Lafortune et al, 2001;Cakir, 2005;Guenette et al, 2007;Ardente et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of MS-222 (Tricaine Methanesulfonate) and Propofol as Anesthetic Agents in Sonoran Desert Toads (Bufo alvarius)

Wojick

Langan

Mitchell

2010

Journal of Herpetological Medicine and Surgery

View full text Add to dashboard Cite

Toads in the genus Bufo are commonly kept in pet, research, and zoological settings and may require anesthesia during veterinary care. Limited information is available comparing anesthetic protocols in most amphibian species. The purpose of this study was to evaluate the clinical and cardiopulmonary effects of tricaine methanesulfonate (MS-222) and propofol in Sonoran desert toads (Bufo alvarius). Nine juvenile Sonoran desert toads were anesthetized with an immersion bath of 1 g/L MS-222 and 35 mg/kg intracoelomic propofol with a minimum 2-wk wash-out period between trials. Heart rate, respiratory rate, and reflexes (righting, escape, corneal, superficial pain, and deep pain) were monitored every 5 min for the first 90 min and then every 10 min for the next 90 min during both anesthetic trials. Surgical anesthesia was defined as complete loss of all measured reflexes. MS-222 produced surgical anesthesia in 100% (9/9) of toads, whereas propofol produced surgical anesthesia in 11.1% (1/9). Mean induction time for the MS-222 trial was 19.9 min (SD: 5.4, Min-Max: 13-30), with mean duration of surgical anesthesia 23.9 min (SD: 10.8, Min-Max: 10-42). Mean recovery time after removal from the MS-222 bath was 85.3 min (SD: 18.5, Min-Max: 60-110). Righting reflex was lost in all animals in the propofol trial at a mean of 23.9 min (SD: 5.5, Min-Max: 20-35) following administration. A single animal in the propofol trial reached a surgical plane of anesthesia at 25 min post-administration, with surgical anesthesia lasting for 50 min. Mean time to recovery following administration of propofol was 145 min (SD: 47.2, Min-Max: 60-180); one toad was not fully recovered at the end of the monitoring period. Heart rate was not found to significantly (P > 0.05) change from baseline at any monitoring point for either anesthetic protocol. Respiratory rate was found to decrease significantly (P < 0.05) at all time points between 5 and 65 min in the MS-222 trial and between 10 and 130 min in the propofol trial. MS-222 at 1 g/L immersion was found to reliably produce surgical anesthesia in Sonoran desert toads with a faster onset of action and recovery when compared to propofol administered intracoelomically at 35 mg/kg.

show abstract

“…When metabolic rate is low and animals are undisturbed, the periods of apnea between breaths or episodes may be extensive. Apneas of up to 8 h have been recorded in resting toads [ Bufo marinus (= Rhinella marina )] resulting in arterial PO 2 of <20 mmHg (Coelho and Smatresk 2003). This suggests that arterial hypoxemia does not necessarily provide a strong ventilatory stimulus under resting conditions and that blood gases are only loosely coupled to ventilation.…”

Section: Amphibiansmentioning

confidence: 99%

Time domains of the hypoxic ventilatory response in ectothermic vertebrates

et al. 2011

View full text Add to dashboard Cite

Over a decade has passed since Powell et al. (Respir Physiol 112:123–134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123–134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O2 supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more ‘holistic’ fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind.

show abstract

Resting respiratory behavior in minimally instrumented toads - effects of very long apneas on blood gases and pH

Cited by 14 publications

References 20 publications

Lung ventilation contributes to vertical lymph movement in anurans

Lung ventilation contributes to vertical lymph movement in anurans

Evaluation of MS-222 (Tricaine Methanesulfonate) and Propofol as Anesthetic Agents in Sonoran Desert Toads (Bufo alvarius)

Time domains of the hypoxic ventilatory response in ectothermic vertebrates

Contact Info

Product

Resources

About