Duration-dependent attenuation of acetylcholine—but not histamine—induced relaxation of the aorta in diabetes mellitus

1. The relaxations of aortic preparations from 1, 4 and 12 week diabetic rats to acetylcholine and histamine were studied. 2. The relaxation to acetylcholine but not to histamine was significantly attenuated in the 4th and 12th weeks of the disease. In addition, the tissues became less sensitive to acetylcholine but not to histamine with increasing duration of the disease. 3. The results show that there is differential alteration in the responsiveness of the aorta from diabetic rats to both agents.