A Newly Isolated Carboxymethyl-Glucan (CM-G) Restores Depressed Baroreflex Sensitivity in Renovascular Hypertensive Rats

Abstract

This study was designed to investigate the effects of a newly synthesized carboxymethyl-glucan (CM-G) on blood pressure (BP), baroreflex sensitivity (BRS) and sympathetic vascular modulation in renovascular hypertensive rats. Male Wistar rats were divided into four groups: Sham (n = 10); 2K1C (subjected to renal artery clipping to induce renovascular hypertension, n = 10); Sham + CM-G (treated with CM-G, n = 7) and 2K1C + CM-G (treated with CM-G, n = 7). The daily treatment with CM-G (40 mg/kg) was performed for 2 weeks. Blood pressure, heart rate (HR), systolic BP variability, baroreflex sensitivity (BRS) and sympathetic vascular tone were evaluated. After six weeks of renal artery clipping, 2K1C rats exhibited arterial hypertension (171 ± 11 vs. 118 ± 4 mmHg, p < 0.05), impaired BRS (-1.30 ± 0.10 vs. -2.59 ± 0.17 bpm.mmHg-1, p < 0.05) and enhanced sympathetic activity as shown by the hexamethonium test (-60 ± 5 vs. -33 ± 2 ΔmmHg, p < 0.05) when compared to sham rats. Oral administration of CM-G in renovascular hypertensive rats reduced hypertension (126 ± 4 vs. 171 ± 11 mmHg, p < 0.05) and improved the BRS (-2.03 ± 0.16 vs. -1.30 ± 0.10 bpm.mmHg-1, p < 0.05) in 2K1C rats when compared to placebo. Those effects seem to be caused by a reduction in sympathetic activity. The present study revealed for the first time that CM-G treatment reduces arterial hypertension and restores arterial baroreflex sensitivity via a reduction in the sympathetic tone in conscious renovascular hypertensive rats.

Central Inhibition of Tumor Necrosis Factor Alpha Reduces Hypertension by Attenuating Oxidative Stress in the Rostral Ventrolateral Medulla in Renovascular Hypertensive Rats

“…However, different of telemetry implantation surgery in the abdominal aorta by laparotomy, which is a major procedure that requires 5–7 days for a full recovery (Greene et al, 2007), implanting of blood vessels catheters via the femoral artery and vein could be considered an ambulatory procedure with just a minor incision on the inguinal region with no major cavity exposure. We have been very successful with this procedure over the last 15 years (Braga and Prabhakar, 2009; Braga, 2010a; Ribeiro et al, 2010; Botelho-Ono et al, 2011; Giusti et al, 2011; Franca-Silva et al, 2012; Guimaraes et al, 2012; Queiroz et al, 2012; Mendes-Junior et al, 2013; Alves et al, 2015; de Queiroz et al, 2015; Cavalcanti et al, 2016; Carvalho-Galvao et al, 2018a)…”

Short‐ and long‐term effects of maternal dyslipidaemia on blood pressure and baroreflex sensitivity in male rat offspring

“…The arterial baroreflex control of sympathetic outflow can be modulated independent of changes in baroreflex control of heart rate . Under pathological conditions, such as arterial hypertension, there is impairment in the autonomic control of blood pressure or heart rate resulting in changes in baroreflex sensitivity …”

“…Baroreflex was also evaluated using classical vasoactive drugs after 50 minutes of BP and HR baseline recordings, phenylephrine (PHE, 8 μg/Kg) and sodium nitroprusside (SNP, 25 μg/Kg) were given as an intravenous bolus injection to the rats in each group to produce abrupt changes in arterial pressure . Injections were not repeated until the recorded parameters had returned to pre‐injection levels.…”

“…28 Under pathological conditions, such as arterial hypertension, there is impairment in the autonomic control of blood pressure or heart rate resulting in changes in baroreflex sensitivity. 9,[29][30][31] Nutritional insults or dysmetabolic condition during pregnancy and/or lactation can alter cardiac baroreflex sensitivity in adult offspring. For example, impaired cardiac baroreflex control associated with increased blood pressure has been observed in male offspring from diabetic dams.…”

Orexin Receptor-1 in the Rostral Ventrolateral Medulla Mediates the Antihypertensive Effects of Electroacupuncture

“…The rats were kept in cages after surgery, maintained on 12 h light/dark cycle with free access to normal chow and tap water. The model was successfully established if systolic BP exceeds 30 mmHg than pre-operation after 4 weeks of operation (Oliveira-Sales et al, 2016; Carvalho-Galvão et al, 2018). In 41 rats with a clipped renal artery, 32 rats were hypertensive and 9 rats were excluded because their BP was not high enough to meet the criterion at 4 weeks after clipping.…”