Effects of angiotensin II and bladder condition on hydration behavior and water uptake in the toad, Bufo woodhousei

Tran, Dinh-Yen; Hoff, Karin vS.; Hillyard, Stanley D.

doi:10.1016/0300-9629(92)90251-k

Cited by 22 publications

(5 citation statements)

References 13 publications

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“…EWL rates of Gila monsters are affected by hydration state (DeNardo et al, 2004), but whether reservoir volume can also influence EWL is unknown. Some toads are able to assess bladder volume and preemptively respond to decreased bladder volume by increasing water absorption behavior (Tran et al, 1992) and water flow across the seat patch (Parsons et al, 1993). Identifying a similar mechanism in lizards in which bladder condition is monitored and water-conserving responses (e.g.…”

Section: Bladder Water Contribution To Osmoregulationmentioning

confidence: 99%

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

Davis

DeNardo

2007

Journal of Experimental Biology

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SUMMARY Animals inhabiting xeric environments use a variety of behavioral and physiological strategies to balance water budgets. We studied the potential contribution of the urinary bladder to osmoregulation in a large desert lizard, the Gila monster Heloderma suspectum. Here we present results of a series of in vivo laboratory experiments which tested the hypothesis that the Gila monster urinary bladder serves as a physiological reservoir, as in amphibians and chelonians, providing water that buffers increases in plasma osmolality when food and water are unavailable. Adult Gila monsters absorbed water from the urinary bladder into circulation and absorption of water from the urinary bladder and drinking water provided similar osmoregulatory benefits within 24 h, although drinking water provided a more immediate osmotic benefit. During food and water deprivation, plasma osmolality increased 2.5 times faster in lizards with an empty urinary bladder compared with those with a full bladder. During rehydration, stereotyped binge drinking behavior increased body mass nearly 22%, which resulted in a 24%reduction in plasma osmolality and a substantial increase in bladder water within 24 h. These results support our hypothesis and demonstrate for the first time in an adult lizard that the urinary bladder can function as a long-term physiological water reservoir. This trait can provide a critical benefit to osmoregulation during the 2- to 3-month summer dry season characteristic of the deserts that Gila monsters inhabit.

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Section: Bladder Water Contribution To Osmoregulationmentioning

confidence: 99%

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

Davis

DeNardo

2007

Journal of Experimental Biology

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“…It should be noted that toads in both of the above studies had their bladders emptied prior to the behavioural trials to obtain a ‘standard weight’ (Ruibal 1962). Tran et al. (1992) showed that an empty bladder alone was sufficient to stimulate WR behaviour and water absorption in hydrated B. woodhouseii and that this effect was further stimulated by AII (Fig.…”

Section: Resultsmentioning

confidence: 91%

“…Injection of the toads with angiotensin II increased water uptake from both groups. Source: Replotted from Tran et al. (1992).…”

Section: Resultsmentioning

confidence: 99%

Chemosensory function of amphibian skin: integrating epithelial transport, capillary blood flow and behaviour

Hillyard

Willumsen

2010

Acta Physiologica

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Terrestrial anuran amphibians absorb water across specialized regions of skin on the posterioventral region of their bodies. Rapid water absorption is mediated by the insertion of aquaporins into the apical membrane of the outermost cell layer. Water moves out of the epithelium via aquaglyceroporins in the basolateral membrane and into the circulation in conjunction with increased capillary blood flow to the skin and aquaporins in the capillary endothelial cells. These physiological responses are activated by intrinsic stimuli relating to the animals' hydration status and extrinsic stimuli relating to the detection of osmotically available water. The integration of these processes has been studied using behavioural observations in conjunction with neurophysiological recordings and studies of epithelial transport. These studies have identified plasma volume and urinary bladder stores as intrinsic stimuli that activate the formation of angiotensin II (AII) to stimulate water absorption behaviour. The coordinated increase in water permeability and capillary blood flow appears to be mediated primarily by sympathetic stimulation of beta adrenergic receptors, although the neurohypopyseal hormone arginine vasotocin (AVT) may also play a role. Extrinsic stimuli relate primarily to the ionic and osmotic properties of hydration sources. Toads avoid NaCl solutions that have been shown to be harmful in acute exposure, approx. 200-250 mm. The avoidance is partially attenuated by amiloride raising the hypothesis that the mechanism for salt detection by toads resembles that for salt taste in mammals that take in water by mouth. In this model, depolarization of the basolateral membrane of taste cells is coupled to afferent neural stimulation. In toad skin we have identified innervation of skin epithelial cells by branches of spinal nerves and measured neural responses to NaCl solutions that elicit behavioural avoidance. These same concentrations produce depolarization of the basolateral membrane in isolated epithelial preparations. As with salt taste in mammals, the neural responses and depolarization of basolateral membrane potential are partially inhibited by amiloride. In addition, toads are more tolerant of sodium gluconate solution which is consistent with the phenomenon in mammalian taste physiology termed the anion paradox in which sodium salts with larger molecular weight anions produce a reduced intensity of salt taste. Finally, toads also avoid concentrated solutions of a non-electrolyte, mannitol, which differs from NaCl solutions in not affecting transepithelial conductance and requires a longer time to depolarize the basolateral membrane. Osmotic stimuli may mediate sensory processes for longer term detection of conditions with low water potential while ionic stimuli are more important for shorter term analysis of rehydration sources.

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“…From this, we can infer that greater osmotic concentrations in surrounding water are physiologically stressful for this species. It is known that dehydration stress (in this study, caused by air or saline media) is an important factor for the increase of frequency or duration of postures associated with water conservation in anurans (Heatwole et al, 1969;Brekke et al, 1991;Hillyard et al, 2007;Pough et al, 1983;Hillyard et al, 1998;Prates et al, 2013;Taylor et al, 1999;Viborg and Rosenkilde, 2001;Tran et al, 1992) Hillyard et al (1998, while studying the physiological processes involved in the behavioral response of Bufo marinus, normally hydrated as well as dehydrated (loss of 10% of initial body mass), and rehydration in NaCl solutions with concentrations of 250 mmol/L and 500 mmol/L, saw that both groups exhibited the "ventral skin down" posture (equivalent to this study's "a" or water conservation posture), but the normally hydrated individuals kept themselves in this posture for a shorter time than individuals which were dehydrated.…”

Section: Discussionmentioning

confidence: 99%

Effects of variations of osmolarity on behavior in Leptodactylus macrosternum Miranda-Ribeiro, 1926 (Leptodactylidae, Anura, Amphibia)

Bonfim

Napoli

Cruz

et al. 2014

reveto

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Amphibians experiencing evapotranspirative water loss may suffer dehydration. Another difficulty is their limited tolerance to brackish water. This study aimed to investigate the effect of water salinity on behavior (activity and water conservation posture) in Leptodactylus macrosternum, in normally hydrated animals with urine in their bladder, in normally hydrated animals without urine in their bladder and in dehydrated ones with urine removed from their bladder. Experiments were filmed, behaviors were registered, and a Behavioral Dehydration Protection Index (BDPI) was calculated, using a weighted average of the postures. A GLM and Kruskall Wallis test was performed with Dunn's multiple comparisons test to evaluate the effects of osmotic gradient stress on BDPI. It was found that emptied bladder and aerial dehydration did not influence BDPI (p = 0.832 and p = 0.142, respectively), contrary to what is seen in the literature. The different osmotic media had a significant effect on BDPI (p = 0.0003). Keywords: Osmotic stress; Leptodacytulus macrosternum; conservation posture.Anfíbios que experimentam perda de água podem sofrer desidratação. Outra dificuldade é a tolerância limitada à água salobra. Este trabalho teve como objetivo estudar o efeito da salinidade da água no comportamento (atividade e postura de conservação de água) de L. macrosternum, normalmente hidratados com urina armazenada na bexiga, normalmente hidratados com urina removida da bexiga e nos desidratados com urina removida da bexiga. Os experimentos foram filmados e foi calculado o índice de proteção comportamental da desidratação (BDPI) usando média ponderada. Realizamos modelo linear generalizado e teste Kruskall-Wallis com comparação múltipla de Dunn, para analisar o efeito dos gradientes de estresse osmótico sobre o BDPI. Observamos que a bexiga esvaziada e a desidratação exercida pelo ar não influenciam o aumento do BDPI (p = 0.832 e p = 0.142, respectivamente) sendo contrário ao visto em literatura. Os diferentes meios osmóticos tiveram efeito sobre o BDPI (p = 0.0003). Palavras-chave: Estresse osmótico; Leptodacytulus macrosternum; postura de conservação.

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Effects of angiotensin II and bladder condition on hydration behavior and water uptake in the toad, Bufo woodhousei

Cited by 22 publications

References 13 publications

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

Chemosensory function of amphibian skin: integrating epithelial transport, capillary blood flow and behaviour

Effects of variations of osmolarity on behavior in Leptodactylus macrosternum Miranda-Ribeiro, 1926 (Leptodactylidae, Anura, Amphibia)

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