Key result
In diabetic hypertensive rats, adding the (pro)renin receptor antagonist handle region peptide to aliskiren counteracted the beneficial vascular effects of renin inhibition.
Why the study?
Does the addition of handle region peptide to aliskiren improve vascular function in diabetic hypertensive rats?
Does the addition of handle region peptide to aliskiren improve vascular function in diabetic hypertensive rats?
In a diabetic hypertensive rat model, (P)RR blockade with HRP counteracted the beneficial vascular effects of renin inhibition, suggesting it is unlikely to be a useful add-on therapy to existing RAS blockers.
HRP counteracted aliskiren vascular benefits in diabetic rats; hypothesis-generating and should not guide clinical use of (P)RR antagonists.
BACKGROUND: Elevated prorenin levels associate with microvascular complications in patients with diabetes mellitus, possibly because prorenin affects vascular function in diabetes mellitus, for example by generating angiotensins following its binding to the (pro)renin receptor [(P)RR]. Here we evaluated whether the renin inhibitor aliskiren, with or without the putative (P)RR antagonist handle region peptide (HRP) improved the disturbed vascular function in diabetic TGR(mREN2)27 rats, a high-prorenin, high-(P)RR hypertensive model. METHODS: Telemetry transmitters were implanted to monitor blood pressure. After 3 weeks of treatment, rats were sacrificed, and iliac and mesenteric arteries were removed to evaluate vascular reactivity. RESULTS: Diabetes mellitus enhanced the contractile response to nitric oxide synthase (NOS) blockade, potentiated the response to phenylephrine, diminished the effectiveness of endothelin type A (ETA) receptor blockade and allowed acetylcholine to display constrictor, cyclo-oxygenase-2 mediated, endothelium-dependent responses in the presence of NOS inhibition and blockers of endothelium-derived hyperpolarizing factors. Aliskiren normalized blood pressure, suppressed renin activity, and reversed the above vascular effects, with the exception of the altered effectiveness of ETA receptor blockade. Remarkably, when adding HRP on top of aliskiren, its beneficial vascular effects either disappeared or were greatly diminished, although HRP did not alter the effect of aliskiren on blood pressure and renin activity. CONCLUSIONS: Renin inhibition improves vascular dysfunction in diabetic hypertensive rats, and HRP counteracts this effect independently of blood pressure and angiotensin. (P)RR blockade therefore is unlikely to be a new tool to further suppress the renin-angiotensin system (RAS) on top of existing RAS blockers.
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Batenburg et al. (2013) studied Diabetes mellitus and hypertension. Aliskiren with or without handle region peptide (HRP) vs. Aliskiren alone or untreated diabetic rats was evaluated on Vascular reactivity and blood pressure. In diabetic hypertensive rats, adding the (pro)renin receptor antagonist handle region peptide to aliskiren counteracted the beneficial vascular effects of renin inhibition.
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