American alligator (Alligator mississippiensis) embryos tightly regulate intracellular pH during a severe acidosis

Canadian Journal of Zoology, e-First Articles. Crocodilian nests naturally experience high CO2 (hypercarbia), which leads to increased blood Pco2 and reduced blood pH (pHe) in embryos; their response to acid –base challenges is not known. During acute hypercarbia, snapping turtle embryos preferentially regulate tissue pH (pHi) against pHe reductions. This is proposed to be associated with CO2 tolerance in reptilian embryos and is not found in adults. In the present study, we investigated pH regulation in American alligator (Alligator mississippiensis (Daudin, 1802)) embryos exposed to 1 h of hypercarbia hypoxia (13 kPa Pco2, 9 kPa Po2). Hypercarbia hypoxia reduced pHe by 0.42 pH unit, while heart and brain pHi increased, with no change in the pHi of other tissues. The results indicate that Ameri can alligator embryos preferentially regulate pHi, similar to snapping turtle embryos, which represents a markedly different strategy of acid–base regulation than what is observed in adult reptiles. These findings suggest that preferential pHi regulation may be a strategy of acid–base regulation used by embryonic reptiles.
Source: Canadian Journal of Zoology - Category: Zoology Authors: Source Type: research