Meeting Abstract

105.3  Thursday, Jan. 7  Cardiovascular plasticity during development in the American alligator (Alligator mississippiensis) EME, J; HICKS, J ; CROSSLEY II, D A*; U Cal Irvine; U Cal Irvine; U N Dakota dane.crossley@und.nodak.edu

The vertebrate cardiovascular (CV) system becomes operational early in embryonic development, and, therefore, must function and continue to mature both anatomically and physiologically. Deviations in the developmental environment may result in challenges that impact CV function and may adjust the pattern of maturation for this critical system. While this is likely a truism across vertebrates, reptilian embryos may be particularly impacted given features of development in these egglaying species. Previously, we have shown that environmental challenges influence the maturation and alter the tonic regulation of baseline CV variables. However, the impact of these challenges on the development of acute regulatory mechanisms, such as a chemoreflex, is unknown. Using stressors that have been previously shown to occur in reptilian nests (reduced oxygen and dehydration), the plasticity of the CV system was assessed in American alligator (A mississippiensis) embryos. Developmental challenge altered physiological CV maturation and morphological development, independent of the incubation stress applied. Acute dehydration events and chronic hypoxic-incubation resulted in a bradycardia at 90% of incubation, but differed in the affect on arterial pressure. Assessments of both a hypoxic and chemically induced chemoreflex indicated the maturation of this regulatory mechanism is plastic during embryonic development and blunted by chronic hypoxic-incubation. Further, the role of the sympathetic and parasympathetic nervous systems is altered by incubation stress. The data indicate that the maturation of CV function exhibits a degree of phenotypic plasticity in the alligator. Supported by NSF Career award IBN IOS-0845741 and NSF IOB 04445680/ 0922756 to JWH