Gastrointestinal and renal responses to variable water intake in whitebellied sunbirds and New Holland honeyeaters

dc.contributor.authorPurchase, Cromwell
dc.contributor.authorNapier, Kathryn R.
dc.contributor.authorNicolson, Sue W.
dc.contributor.authorMcWhorter, Todd J.
dc.contributor.authorFleming, Patricia A.
dc.date.accessioned2013-06-12T07:16:24Z
dc.date.available2013-06-12T07:16:24Z
dc.date.issued2013
dc.description.abstractNectarivores face a constant challenge in terms of water balance, experiencing water loading or dehydration when switching between food plants or between feeding and fasting. To understand how whitebellied sunbirds and New Holland honeyeaters meet the challenges of varying preformed water load, we used the elimination of intramuscular-injected [14C]-L-glucose and 3H2O to quantify intestinal and renal water handling on diets varying in sugar concentration. Both sunbirds and honeyeaters showed significant modulation of intestinal water absorption, allowing excess water to be shunted through the intestine when on dilute diets. Despite reducing their fractional water absorption, both species showed linear increases in water flux and fractional body water turnover as water intake increased (both afternoon and morning), suggesting that the modulation of fractional water absorption was not sufficient to completely offset dietary water loads. In both species, glomerular filtration rate was independent of water gain (but was higher for the afternoon), as was renal fractional water reabsorption (measured in the afternoon). During the natural overnight fast, both sunbirds and honeyeaters arrested whole kidney function. Evaporative water loss in sunbirds was variable but correlated with water gain. Both sunbirds and honeyeaters appear to modulate intestinal water absorption as an important component of water regulation to help deal with massive preformed water loads. Shutting down glomerular filtration rate during the overnight fast is another way of saving energy for osmoregulatory function. Birds maintain osmotic balance on diets varying markedly in preformed water load by varying both intestinal water absorption and excretion through the intestine and kidneys.en
dc.description.librarianam2013en
dc.description.librarianab2013
dc.description.sponsorshipThis project was funded by the National Research Foundation of South Africa, the University of Pretoria and the Australian Research Council (DP0665730).en
dc.description.urihttp://jeb.biologists.org/en
dc.identifier.citationPurchase, C, Napier, KR, Nicolson, SW, McWhorter, TJ & Fleming, PA 2013, 'Gastrointestinal and renal responses to variable water intake in whitebellied sunbirds and New Holland honeyeaters', Journal of Experimental Biology, vol. 216, no. 9, pp. 1537-1545.en
dc.identifier.issn0022-0949 (print)
dc.identifier.issn1477-9145 (online)
dc.identifier.other10.1242/jeb.075176
dc.identifier.urihttp://hdl.handle.net/2263/21613
dc.language.isoenen
dc.publisherCompany of Biologistsen
dc.rights© 2013. Published by The Company of Biologists Ltden
dc.subjectWater balanceen
dc.subjectOsmoregulationen
dc.subjectIntestinal water absorptionen
dc.subjectRenal functionen
dc.subjectNectarivoreen
dc.subject.lcshSunbirdsen
dc.subject.lcshHoneyeatersen
dc.subject.lcshPasseriformesen
dc.subject.lcshWater in the bodyen
dc.subject.lcshBody fluidsen
dc.subject.lcshPharmacokineticsen
dc.titleGastrointestinal and renal responses to variable water intake in whitebellied sunbirds and New Holland honeyeatersen
dc.typeArticleen

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