The anatomical distribution of ADPase activity in the rabbit aorta.

The anatomical distribution of ADPase activity in the rabbit aorta was investigated. The aortic arch and upper thoracic regions of the rabbit aorta were found to have a reduced capacity to break down ADP and also unable to further metabolise the AMP thus formed. ADPase activity progressively increased down the aorta to the abdominal regions where it was highest. The abdominal regions of the aorta together with the lower thoracic region were able to produce adenosine from ADP. These results suggest a connection between ADPase activity and the incidence of atherosclerosis in rabbits. Thus in the aortic arch and upper thoracic regions of the aorta where the incidence of the disease is higher, the ability of the vascular tissue to break down ADP is low; therefore platelet aggregation is more likely to occur in response to minimal wear and tear. Conversely, in the abdominal regions where ADPase activity is highest and the incidence of the disease is lower ADPase may play a protective role in limiting ADP-induced thrombotic response to vascular trauma.