Meeting Abstract
P3.11 Saturday, Jan. 5 The Impact of Chronic Hypoxic Incubation On Cardiovascular Physiology of Embryonic Common Snapping Turtles (Chelydra serpentina). CROSSLEY, Dane A; University of North Dakota dane.crossley@und.nodak.edu
In response to chronic hypoxic incubation reptilian embryos are known to alter incubation length, embryonic mass, hematological parameters and metabolic rate. In addition embryonic American alligators incubated in hypoxic conditions are known to exhibit a depression of resting arterial pressure and heart rate. However, these reductions in baseline cardiovascular physiology are not attributed to an alteration in cholinergic or beta adrenergic tone on the heart. While this is known in embryonic alligators the degree to which this response represents that of other embryonic reptiles is unknown. Therefore, the impact of chronic hypoxic incubation (10% O2) on autonomic cardiovascular tone was studied in embryos of the common snapping turtle at 90 % of development. Snapping turtle eggs of approximately 2 weeks of age from each of 4 clutches were equally distributed between two oxygen conditions (21% and 10% O2) and incubated at 30 degrees C. At 90% of development eggs from each condition were assessed pharmacologically for autonomic tone. Chronic incubation in 10% O2 resulted in resting arterial pressure that was slightly elevated compared to normoxic incubation (1.10 vs. 0.94 kPa respectively) and resting heart rate (fH) was similar between the two groups (?54 vs. 51 min-1 respectively). Cardiovascular responses to cholinergic blockade (atropine 1 mg/kg) differed between the groups. However the cardiovascular response to both addition alpha and beta-adrenergic blockade (phentolamine 3 mg/kg and propranolol 3 mg/kg respectively) were similar between the experimental incubations conditions. Collectively the data indicate that chronic incubation under hypoxic conditions results in a change in cholinergic tone at 90% of incubation without altering adrenergic tone on the cardiovascular system of embryonic snapping turtles.
