Meeting Abstract

P3.49  Sunday, Jan. 6  Dehydration stress during embryonic development alters autonomic regulation of the cardiovascular system in the American alligator (Alligator mississippiensis) TATE, KB*; CROSSLEY II, DA ; Univ. North Texas; Univ. North Texas kevtate@gmail.com

The incubation environment has a profound influence on development. Egg-laying amniotes, such as the American alligator (Alligator mississippiensis), develop within an egg case that may be particularly susceptible to changes in the local nest environment. Hydric conditions in the alligator nest have been documented to change based on seasonal conditions. In laboratory studies, alligator embryos exposed to dehydration events are markedly smaller and have altered cardiovascular function late in incubation. Thus, the current study was undertaken to determine if autonomic regulation of embryonic cardiovascular function is altered by dehydration stress during development. We hypothesized that the previously reported relative bradycardic response to chronic dehydration was the result of early maturation of vagal tone on the system. Dehydration events produced similar morphological changes as previously reported and resulted in vagal tone depressing resting heart rate during the final 10% of incubation. Angiotensin II (Ang II), a key water conservation humoral regulatory peptide, produced a hypertensive bradycardia when delivered. Treatment with atropine, a cholinergic antagonist, abolished the bradycardic response suggesting activation of the vagus in response to the Ang II induced hypertension. Treatment with phentolamine, an alpha adrenergic antagonist, attenuated the Ang II hypertensive response. Collectively it appears that dehydration alters autonomic regulation of heart rate, while the mechanisms of the Ang II response are unaffected. NSF CAREER IBN IOS-0845741 to DAC