in vitro
bilateral microinjection of rilmenidine into the c1 area of the rostral ventrolateral medulla (rvl) elicited dose-dependent falls in arterial pressure and heart rate. in rvl, rilmenidine competed with binding to imidazole and α2-adrenergic binding sites with a 30-fold selectivity for the imidazole binding sites [2]. rilmenidine, a new antihypertensive agent, appeared 2.5 and 3.5 times more selective than clonidine and guanfacine, respectively, for medullary ipr sites than for cortical α-adrenoceptors [3]. rilmenidine targeted the nonadrenergic imidazoline-binding site i1 receptor with the ki value of 7.1 nm and demonstrated weaker affinity for the i2 receptor with the ki value of 5.2 μm [4].
in vivo
in rat model of hypertension associated with insulin resistance, rilmenidine ameliorated the deleterious effects of a high-fructose diet, such as weight gain, hypertension, and resistance to the effects of insulin [5]. in a mouse model of huntington's disease, rilmenidine induced autophagy, attenuated toxicity of polyglutamine expansions and the signs of disease, reduced the mutant huntingtin fragment levels [6].
References
[1] reis, d. j. and piletz, j.e. the imidazoline receptor in control of blood pressure by clonidine and allied drugs. american journal of physiology 273(5 pt 2), r1569-r1571 (1997).
[2] gomez r e, ernsberger p, feinland g, et al. rilmenidine lowers arterial pressure via imidazole receptors in brainstem c1 area[j]. european journal of pharmacology, 1991, 195(2): 181-191.
[3] bricca g, dontenwill m, molines a, et al. rilmenidine selectivity for imidazoline receptors in human brain[j]. european journal of pharmacology, 1989, 163(2): 373-377.
[4] guyenet p g. is the hypotensive effect of clonidine and related drugs due to imidazoline binding sites [j]. american journal of physiology-regulatory, integrative and comparative physiology, 1997, 273(5): r1580-r1584.
[5] penicaud l, berthault m f, morin j, et al. rilmenidine normalizes fructose-induced insulin resistance and hypertension in rats[j]. journal of hypertension. supplement: official journal of the international society of hypertension, 1998, 16(3): s45-9.
[6] rose c, menzies f m, renna m, et al. rilmenidine attenuates toxicity of polyglutamine expansions in a mouse model of huntington's disease[j]. human molecular genetics, 2010, 19(11): 2144-2153.