Blood pressure reduction induced by chronic intracerebroventricular or peroral clonidine administration in rats with salt-dependent or angiotensin II-dependent hypertension

0565796 - FGÚ 2023 RIV CZ eng J - Journal Article
Zicha, Josef - Řezáčová, Lenka - Behuliak, Michal - Vaněčková, Ivana
Blood pressure reduction induced by chronic intracerebroventricular or peroral clonidine administration in rats with salt-dependent or angiotensin II-dependent hypertension.
Physiological Research. Roč. 71, č. 6 (2022), s. 763-770. ISSN 0862-8408. E-ISSN 1802-9973
R&D Projects: GA ČR(CZ) GC19-08260J; GA MŠMT(CZ) LX22NPO5104
Institutional support: RVO:67985823
Keywords : central alpha2-adrenergic receptors * sympathetic tone * Dahl saltsensitive rats * Ren-2 transgenic rats * vasoactive systems * renin-angiotensin system * sympathetic nervous system * nitric oxide
OECD category: Physiology (including cytology)
Impact factor: 2.1, year: 2022
Method of publishing: Open access
https://www.biomed.cas.cz/physiolres/pdf/2022/71_763.pdf

The agonists of alpha(2)-adrenergic receptors such as clonidine, rilmenidine or monoxidine are known to lower blood pressure (BP) through a reduction of brain sympathetic outflow but their chronic antihypertensive effects in rats with low-renin or high-renin forms of experimental hypertension were not studied yet. Moreover, there is no comparison of mechanisms underlying BP reduction elicited by chronic peroral (po) or intracerebroventricular (icv) clonidine treatment. Male salt-sensitive Dahl rats fed 4% NaCl diet and Ren-2 transgenic rats were treated with clonidine administered either in the drinking fluid (0.5 mg/kg/day po) or as the infusion into lateral brain ventricle (0.1 mg/kg/day icv) for 4 weeks. Basal BP and the contributions of renin-angiotensin system (captopril 10 mg/kg iv) or sympathetic nervous system (pentolinium 5 mg/kg iv) to BP maintenance were determined in conscious cannulated rats at the end of the study. Both peroral and intracerebroventricular clonidine treatment lowered BP to the same extent in either rat model. However, in both models chronic clonidine treatment reduced sympathetic BP component only in rats treated intracerebroventricularly but not in perorally treated animals. In contrast, peroral clonidine treatment reduced angiotensin II-dependent vasoconstriction in Ren-2 transgenic rats, whereas it lowered residual blood pressure in Dahl rats. In conclusions, our results indicate different mechanisms of antihypertensive action of clonidine when administered centrally or systemically.
Permanent Link: https://hdl.handle.net/11104/0337282