Cardiac response to stimulation and stress in the American alligator (Alligator mississippiensis)

Abstract

Abstract Previous descriptions of the direction (tachycardia versus bradycardia), magnitude, and duration of the cardiac stimulation/stress response of the American alligator (Alligator mississippiensis) have been contradictory. Superficial EKG leads were used to quantify heart rate while presenting a graded series of stimuli to a cohort of 5 sub-adult alligators. Only tachycardic responses were recorded. Stress (manual restraint and transport) induced a nearly 3-fold increase over the resting heart rate (∼17 bpm), which decreased only 7 bpm over 40 minutes in a stimulus-free environment. Lower-level stimulation (i.e., exposure to room light) produced a significantly smaller response than did higher-level stimulation (i.e., physical contact), both responses were transitory, lasting approximately 120 s.