Atividade vasorelaxante e anti-hipertensiva de LQM01, um novo derivado aminoguanidínico, em ratos espontaneamente hipertensos

Abstract

The literature reports beneficial effects of aminoguanidine and its derivatives on the cardiovascular system. This work utilized strategies of Medicinal Chemistry, such as molecular hybridization and bio-ossification, for the synthesis of 14 aromatic aminoguanidine derivatives (DAGs), in order to investigate effective, safe and less effective adverse therapeutic alternatives for the treatment of hypertension. After pharmacological screening with the 14 DAGs, in order to select the most efficient derivative with respect to its cytotoxic activity and vasorelaxant effect, the work follows with the characterization of the cardiovascular effects induced by LQM01 in Spontaneously Hypertensive Rats (SHR), Through experimental approaches in vitro and in vivo, using the method of preparations with superior mesenteric artery isolated from rat and direct and indirect blood pressure measurement, respectively. The LQM01 derivative showed very low cytotoxic activity in MTT assays with reduced cell growth only at high concentrations. The derivative 01 also promoted a vasorelaxant effect similar to the Guanabenzo antihypertensive drug, a positive control, in rings pre-contracted with FEN, independently of endothelium. The observed effect showed a significant deviation of the response curve from LQM01 to the right, in precontracted FEN rings, in the presence of the 5 mM TEA blocker, a non-selective blocker of the K+ channels of the 4-AP blocker, a blocker (1mM) and TEA 1mM, a selective BKCa blocker, thus suggesting the participation of KV, BKCa in the vasorelaxation effect induced by LQM01. As in the depolarizing solution of KCl 80mM vasorelaxation was reduced, suggesting the inhibition of Ca2+ influx through the VOCCs, such hypothesis is justified by the attenuation of the CaCl2-induced contractions in the depolarizing solution nominally without Ca+2. In non-anesthetized SHR rats, i.v. in bolus administration of LQM01 induced dose-dependent hypotension with a more significant hypotensive effect at doses of 5 and 10 mg/kg, accompanied by an intense bradycardic effect. However, after CNS depression in the group of animals anesthetized with sodium thiopental, both the hypotensive and bradycardic responses induced by the derivative were attenuated or virtually abolished, respectively. In addition, the LMQ01 derivative was able to promote antihypertensive activity, at doses of 5 and 10 mg/kg, by its orogastric administration from the second hour, but at the fourth and sixth hour only at the highest dose, without Significant changes in HR at both doses. Conclusion: The data suggest that LQM01 promotes vasodilator effect through channel stimulation for K+, Kv and BKCa, besides inhibiting Ca2+ influx, possibly through blocking VOCCs, as well as promoting hypotensive, bradycardic and anti- Hypertensive, which may be due to a direct action of the substance on the MLV, inducing vasorelaxation and consequent reduction of peripheral vascular resistance, contributing to its hypotensive action, but may also have an inhibitory influence on the neural control system that acts on the cardiovascular system.