March 24, 2011: INBRE stress physiology candidate speaks on 'Beating Without Oxygen'

Thursday, March 24, 4 p.m.
Administration Building, Room 204

INBRE (IDeA Network of Biomedical Research Excellence) candidate Dr. Jonathan Stecyk speaks on, "Beating Without Oxygen: Cardiovascular Status and Its Control in the Champions of Prolonged Anoxia Survival."

Here is a description of Stecyk's talk:

Most vertebrates die within minutes when deprived of molecular oxygen (anoxia) because the heart and brain requires a continuous supply of oxygen. However, a relatively few vertebrate species exhibit the remarkable ability to survive anoxia for hours, days and even months.

Among them, the freshwater turtle (Trachemys scripta) and crucian carp (Carassius carassius) are undoubtedly the most impressive examples. These species overwinter in ice-covered ponds, which become progressively hypoxic (low oxygen) and ultimately anoxic, as thick ice coverage inhibits both photosynthesis and oxygen diffusion from the air. Yet, under these conditions, their heart continues to function.

This research focuses on understanding how this is possible and how the cardiovascular system of anoxic turtle and carp is regulated. To survive prolonged anoxia, the freshwater turtle enters a severe hypometabolic state.

Correspondingly, cardiac activity is massively reduced. At cold temperature, the heart contracts less than once a minute. The slowing of heart rate is mediated by a number of extrinsic and intrinsic factors. Unlike the turtle, the crucian carp remains active during anoxia, albeit at a reduced level. Correspondingly, the fish exhibits the seemingly unique ability among vertebrates to maintain cardiac activity at normoxic levels.

Further, autonomic control of the heart remains intact. These responses point to an unprecedented tolerance of a vertebrate heart and autonomic nervous system to prolonged anoxia. Continued research into how the heart and peripheral circulation of anoxic turtles and crucian carp is controlled promises to expand our mechanistic comprehension of vertebrate cardiovascular systems that have evolved the ability to function in the presence of little or no oxygen.