Comp Biochem Physiol A Mol Integr Physiol
November 2024
Numerous studies report on the influence of temperature on blood gases in ectothermic vertebrates, but there is merely a cursory understanding of these effects in developing animals. Animals that develop in eggs are at the mercy of environmental temperature and are expected to lack the capacity to regulate gas exchange and may regulate blood gases by means of altered conductance for gas exchange. We, therefore, devised a series of studies to characterize the developmental changes in blood gases when embryonic alligators were exposed to 25, 30 and 35 °C.
View Article and Find Full Text PDFAssessments of arterial and venous blood gases are required to understand the function of respiratory organs in animals at different stages of development. We measured blood gases in the arteries entering and veins leaving the chorioallantoic membrane (CAM) in embryonic alligators (Alligator mississippiensis). The CAM accounts for virtually all gas exchange in these animals, and we hypothesized that the CAM vasculature would be larger in eggs incubated in hypoxia (10% O for 50% or 70% of incubation), which would be reflected in a lower partial pressure of CO (PCO).
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
August 2023
The developmental environment can alter an organism's phenotype through epigenetic mechanisms. We incubated eggs from American alligators in 10% O (hypoxia) to investigate the functional plasticity of blood flow patterns in response to feeding later in life. Digestion is associated with marked elevations of metabolism, and we therefore used the feeding-induced stimulation of tissue O demand to determine whether there are lasting effects of developmental hypoxia on the cardiovascular response to digestion later in life.
View Article and Find Full Text PDFReptiles have the capacity to differentially perfuse the systemic and pulmonary vascular circuits via autonomic regulation of the heart and the vascular trees. While this aptitude is widely recognized, the role of 'shunting' as a homeostatic mechanism to match convective transport with tissue demand remains unknown. In crocodilians, it has been hypothesized that a pulmonary vascular bypass of systemic venous blood - a right-to-left (R-L) shunt - serves to deliver CO-rich blood with protons needed for gastric acid secretion during digestion.
View Article and Find Full Text PDFThe electrocardiogram (ECG) reveals that heart chamber activation and repolarization are much faster in mammals and birds compared to ectothermic vertebrates of similar size. Temperature, however, affects electrophysiology of the heart and most data from ectotherms are determined at body temperatures lower than those of mammals and birds. The present manuscript is a review of the effects of temperature on intervals in the ECG of ectothermic and endothermic vertebrates rather than a hypothesis-testing original research article.
View Article and Find Full Text PDFMammals and birds have a specialized cardiac atrioventricular conduction system enabling rapid activation of both ventricles. This system may have evolved together with high heart rates to support their endothermic state (warm-bloodedness) and is seemingly lacking in ectothermic vertebrates from which first mammals then birds independently evolved. Here, we studied the conduction system in crocodiles (), the only ectothermic vertebrates with a full ventricular septum.
View Article and Find Full Text PDFVertebrates reduce arterial blood pH (pHa) when body temperature increases. In water breathers, this response occurs primarily by reducing plasma HCO levels with small changes in the partial pressure of CO ( ). In contrast, air breathers mediate the decrease in pHa by increasing arterial (a ) at constant plasma HCO by reducing lung ventilation relative to metabolic CO production.
View Article and Find Full Text PDFReduced oxygen availability (hypoxia) is a potent stressor during embryonic development, altering the trajectory of trait maturation and organismal phenotype. We previously documented that chronic embryonic hypoxia has a lasting impact on the metabolic response to feeding in juvenile snapping turtles (). Turtles exposed to hypoxia as embryos [10% O (H10)] exhibited an earlier and increased peak postprandial oxygen consumption rate, compared with control turtles [21% O (N21)].
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
January 2017
Chronic hypoxic incubation is a common tool used to study developmental changes in reduced O conditions, and it has been useful for identifying phenotypically plastic periods during ontogeny in laboratory settings. Reptilian embryos can be subjected to natural hypoxia due to nesting strategy, and recent studies have been important in establishing the phenotypic responses of several species to low developmental oxygen. In particular, the cardiovascular responses of American alligators (Alligator mississippiensis) to low developmental oxygen have been detailed, including a substantial cardiac enlargement that may support a higher mass specific metabolic rate.
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