Physiology Dept., Usman Danfodio University, Sokoto.
Usmanu Danfodiyo University, Sokoto, Nigeria.
Niger J Physiol Sci. 2022 Jun 30;37(1):147-152. doi: 10.54548/njps.v37i1.18.
The aqueous calyx extract of Hibiscus sabdariffa (HS) is widely consumed as a beverage in Northern Nigeria and other parts of the world. HS has been reported to lower blood pressure (BP) in animals and man. However, not much is known about the effect of HS on BP in different postures. We tested the hypothesis that HS may lower BP, heart rate (HR) and heart rate-pressure product or double product (DP) by attenuating the discharge of the autonomic nervous system in different postures. Experiments were performed in accordance with the Principles of the Declaration of Helsinki. Following ethical approval and informed consent, BP and HR were measured in different postures (supine, sitting and standing) in apparently healthy human subjects (n=20) before and after (+HS) the oral administration of 15mg/Kg HS. Mean arterial pressure (MAP; taken as representative BP) and DP were calculated. Results are expressed as mean ±SEM. Paired t test and ANOVA with a post hoc Bonferroni test were used for statistical analyses. P<0.05 was considered significant. In the supine position MAP, HR and DP were significantly (P<0.0001 each) reduced in the presence of HS (85.6±1.7mmHg, 72.1±1.1/min and 8716±320mmHg.bpm) compared to its absence (89.6±2.0mmHg, 73.7±1.6/min and 8921±444mmHg.bpm). Similar trends were observed in the sitting position in the presence of HS (85.4±2.7mmHg, 73.7±1.8/min and 9098±345mmHg.bpm vs its absence: 91.4±2.3mmHg, 77.1±1.9/min and 9388±478mmHg.bpm; P<0.0001, P<0.0001 and P=0.007 respectively) and in the standing position (+HS: 89.3±2.0mmHg, 78.1±1.8/min and 10164±230mmHg.bpm vs its absence: 94.3±2.1mmHg, 81.8±2.3/min and 10742±268mmHg.bpm; P<0.0001, P<0.0001 and P=0.007 respectively). In the absence of HS, HR and DP were significantly higher in the standing posture (81.8±2.3/min, 10742±268mmHg.bpm) compared to the sitting (77.1±1.9/min, 9388±478mmHg.bpm; P<0.05 and P<0.0001 respectively) and the supine (73.7±1.6/min, 8921±444mmHg.bpm; P<0.001 each) postures while the BP remained similar. A similar trend was observed across the three postures in the presence of HS although the parameters were significantly lower. It is concluded that HS lowered BP, HR and DP by modulating autonomic mechanisms through the inhibition of both parasympathetic withdrawal and sympathetic nervous system discharge across the postures. Also the standing posture is associated more with a higher sympathetic nervous system discharge and a higher cardiac oxygen demand and workload than the sitting and supine postures in the absence or presence of HS.
藏红花（HS）的水萼提取物在尼日利亚北部和世界其他地区被广泛用作饮料。据报道，HS 可降低动物和人类的血压（BP）。然而，关于 HS 在不同姿势下对 BP 的影响知之甚少。我们假设 HS 可能通过减轻自主神经系统在不同姿势下的放电来降低 BP、心率（HR）和心率-压力乘积或双乘积（DP）。实验是按照《赫尔辛基宣言》的原则进行的。在获得伦理批准和知情同意后，在口服 15mg/Kg HS 前后，在 20 名健康人类受试者中测量不同姿势（仰卧、坐姿和站立）下的 BP 和 HR。平均动脉压（MAP；作为代表性 BP 测量）和 DP 进行了计算。结果表示为平均值±SEM。采用配对 t 检验和方差分析（事后 Bonferroni 检验）进行统计分析。P<0.05 被认为具有统计学意义。在仰卧位，HS 存在时 MAP、HR 和 DP 显著降低（各 P<0.0001）（85.6±1.7mmHg、72.1±1.1/min 和 8716±320mmHg.bpm）与不存在 HS 时相比（89.6±2.0mmHg、73.7±1.6/min 和 8921±444mmHg.bpm）。在 HS 存在时，坐姿也观察到类似的趋势（85.4±2.7mmHg、73.7±1.8/min 和 9098±345mmHg.bpm 与不存在 HS 时相比：91.4±2.3mmHg、77.1±1.9/min 和 9388±478mmHg.bpm；P<0.0001、P<0.0001 和 P=0.007），站立位时（+HS：89.3±2.0mmHg、78.1±1.8/min 和 10164±230mmHg.bpm 与不存在 HS 时相比：94.3±2.1mmHg、81.8±2.3/min 和 10742±268mmHg.bpm；P<0.0001、P<0.0001 和 P=0.007）。在没有 HS 的情况下，站立位时 HR 和 DP 明显高于坐姿（81.8±2.3/min、10742±268mmHg.bpm）和仰卧位（77.1±1.9/min、9388±478mmHg.bpm；P<0.05 和 P<0.0001），而 BP 则相似。在 HS 存在的情况下，也观察到了类似的趋势，但参数明显较低。这表明 HS 通过抑制副交感神经的撤退和交感神经系统的放电，在不同的姿势下降低了 BP、HR 和 DP。此外，与仰卧位和坐姿相比，站立位与更高的交感神经放电以及更高的心脏氧需求和工作量相关，无论是否存在 HS。
