Dr. Kyra J. Cowan
Dear Dr. Grover;
Thank you. There is not an actual increase in the amount of PKA during anoxia, or during the onset of anoxic conditions. During the initial stages of anoxia, i.e. the first two hours of exposure to anoxic conditions, the crayfish responds to the lack of oxygen by increasing the percentage of active PKAc, BUT the total amount of enzyme stays constant. With the drop in oxygen levels, metabolic rate overall will fall dramatically (eg. looking at heat production). However, the anaerobic breakdown of glycogen may actually rise in the short term (eg. an increase in lactate levels). The rise in PKA (% active) activity is likely associated with an increase in AC activity and therefore an increase in cAMP levels. TOTAL PKAc levels, however, are not affected.