Physiology Dept., Usman Danfodio University, Sokoto.
Usmanu Danfodiyo University, Sokoto, Nigeria.
Niger J Physiol Sci. 2021 Dec 31;36(2):203-209. doi: 10.54548/njps.v36i2.9.
This study tested the hypothesis that the hypotensive effect of the aqueous calyx extract of Hibiscus sabdariffa (HS) occurs through autonomic mechanisms that may be associated with a reduction in the double product (DP) of the heart. Experiments were performed in accordance with the Principles of the Declaration of Helsinki. Following ethical approval and informed consent, the Harvard step test (HST) was performed in healthy subjects (n=14) to activate the autonomic nervous system before and after the oral administration of 15mg/kg HS. The blood pressure (BP) and heart rate (HR) responses were measured and DPs and the mean arterial pressure (MAP) were calculated. Results were expressed as mean ±SEM. Paired t-test and one way ANOVA with a posthoc Bonferoni test were used for statistical analyses. P<0.05 was considered significant. HST without HS resulted in a significant rise in MAP, HR and DP (112.6±2.7mmHg, 97.7±2.5/min and 12630.0±642 mmHg.bpm) from the basal values (98.5±2.3mmHg, 76.5±2.0/min and 8730.7±354.9 mmHg.bpm, P<0.001, P<0.01 and P<0.001 respectively). In the presence of HS, HST-induced changes (∆MAP=7.8±1.6mmHg; ∆HR=8.1±1.6/min; ∆DP= 1113.6±103.4 mmHg.bpm) were significantly dampened compared to its absence (∆MAP= 13.3±2.6mmHg; ∆HR=17.0±3.7/min; ∆DP= 3899.3±287.2 mmHg.bpm; P<0.001, P<0.01 and P<0.0001 respectively). The HST-induced increase in BP, HR and DP suggest sympathetic nervous system (SNS) activation and parasympathetic nervous system (PNS) withdrawal associated with an increased cardiac O2 consumption and workload. These were dampened by HS suggesting that its hypotensive effect occurs through the inhibition of SNS activation, PNS withdrawal and an associated reduction in cardiac O2 demand and workload.
本研究旨在验证以下假设，即罗望子（Hibiscus sabdariffa）水浸提物的降压作用是通过自主神经机制实现的，这可能与心脏双乘积（DP）的降低有关。实验是按照《赫尔辛基宣言》的原则进行的。在伦理批准和知情同意后，对 14 名健康受试者进行哈佛台阶试验（HST），以在口服 15mg/kg 罗望子提取物前后激活自主神经系统。测量血压（BP）和心率（HR）反应，并计算 DP 和平均动脉压（MAP）。结果以平均值±SEM 表示。采用配对 t 检验和单因素方差分析（事后 Bonferroni 检验）进行统计学分析。P<0.05 被认为具有统计学意义。没有罗望子的 HST 导致 MAP、HR 和 DP 显著升高（从基础值分别升高 112.6±2.7mmHg、97.7±2.5/min 和 12630.0±642mmHg.bpm，P<0.001、P<0.01 和 P<0.001）。在存在罗望子的情况下，与不存在罗望子时相比，HST 引起的变化（∆MAP=7.8±1.6mmHg；∆HR=8.1±1.6/min；∆DP=1113.6±103.4mmHg.bpm）明显减弱（∆MAP=13.3±2.6mmHg；∆HR=17.0±3.7/min；∆DP=3899.3±287.2mmHg.bpm；P<0.001、P<0.01 和 P<0.0001）。HST 引起的血压、心率和 DP 的增加表明交感神经系统（SNS）激活和副交感神经系统（PNS）抑制与心脏 O2 消耗和工作量增加有关。这些都被罗望子抑制，这表明其降压作用是通过抑制 SNS 激活、PNS 抑制以及相关的心脏 O2 需求和工作量减少来实现的。
