Antihypertensive action of allantoin in animals




        The agonists of imidazoline I-1receptors (I-1R) are widely used to lower blood pressure. It has been indicatedthat guanidinium derivatives show an ability to activate imidazoline receptors.Also, allantoin has a chemical stricture similar to guanidinium derivatives.Thus, it is of special interesting to characterize the effect of allantoin on I-1R.In conscious male spontaneous hypertensive rats (SHRs), mean blood pressure(MBP) was recorded using the tail-cuff method. Furthermore, the hemodynamicanalyses in catheterized rats were applied to measure the actions of allantoinin vivo. Allantoin decreased blood pressures in SHRs at 30 minutes, as the mosteffective time. Also, this antihypertensive action showed in a dose-dependentmanner from SHRs treated with allantoin. Moreover, in anesthetized rats,allantoin inhibited cardiac contractility and heart rate as showing inhemodynamic dP/dt max significantly. Also, the peripheral blood flow was markedincreased by allantoin. Both actions were diminished by efaroxan at the dosesufficient to block I-1R. Thus, we suggest that allantoin, as I-1R agonist; hasthe potential to develop as a new therapeutic agent for hypertension in thefuture.


Key words: allantoin; imidazoline I-1 receptor; hypertension; peripheral bloodflow; cardiac contractility