Adenosine: Biphasic dose responses

This article characterizes the occurrence of biphasic dose responses by ade nosine and its stable analogs in numerous systems, including the respirator y tract, kidney, cardiovascular system, and brain. Considerable mechanistic research on various systems explored and clarified the interactions of the A-1 and A-2 receptors and their interactive influence on the occurrence of the biphasic dose responses. In general, the maximum stimulatory response was 2.5-fold or less than controls, while the stimulatory concentration ran ge was quite variable ranging from 10- to 10(5)-fold.