Responses of the isolated aortic rings of rats to some vasoactive agents
Isolated aortic ring preparations have been used extensively to evaluate the vascular function in health and disease, and are especially well suited to high-throughput studies of vascular reactivity. Methods included contraction of aortic rings with PE (10-5 M) and recording the changes after increasing the concentrations of acetylcholine (Ach) and sodium nitroprusside (SNP) (10-8 -10-4 M). Similar experiments were conducted after incubation of the aortic rings with 2׳, 5׳ dideoxy adenosine (DDA), methylene blue (MB) and L-N nitroarginine (L- NNA) in the three different channels and thereafter relaxed these with forskolin (FSK) and SNP. The results showed that acetylcholine and sodium nitroprusside caused dose-dependent relaxation of the aortic rings of rats. The incubation of the rings with L-NNA completely blocked the relaxation effect of forskolin and that of DDA caused partial blockade of relaxation effect of forskolin. Incubation of the aortic rings with methylene blue could not cause any blockade of relaxation effect of sodium nitroprusside. The vascular responses of the vasoactive agents recorded from this study showed that this assay should thus be continually deployed in investigating the vascular responses of vasoactive agents in the human and animal body as this may bring about the discovery of lead drugs in particular from natural products of plant sources.
Keywords: Aortic ring assay, PE, SNP, Ach, DDA, L-NNA, Vasoactive agents