The Aqueous Calyx Extract of Hibiscus sabdariffa Lowers Blood Pressure and Heart Rate via Sympathetic Nervous System Dependent Mechanisms

Summary: The antihypertensive effect of Hibiscus sabdariffa (HS) has been validated in animals and man. This study tested the hypothesis that its hypotensive effect may be sympathetically mediated. The cold pressor test (CPT) and handgrip exercise (HGE) were performed in 20 healthy subjects before and after the oral administration of 15mg/Kg HS. The blood pressure (BP) and heart rate (HR) responses were measured digitally. Mean arterial pressure (MAP; taken as representative BP) was calculated. Results are expressed as mean ±SEM. P<0.05 was considered significant. CPT without HS resulted in a significant rise in MAP and HR (111.1±2.1mmHg and 100.8±2.0/min) from the basal values (97.9±1.9mmHg and 87.8±2.1/min; P<0.0001 respectively). In the presence of HS, CPT-induced changes (ΔMAP=10.1±1.7mmHg; ΔHR= 8.4±1.0/min) were significantly reduced compared to its absence (ΔMAP= 13.2±1.2mmHg; ΔHR= 13.8±1.6/min; P<0.0001 respectively). The HGE done without HS also resulted in an increase in MAP and HR (116.3±2.1mmHg and 78.4±1.2/min) from the basal values (94.8±1.6mmHg and 76.1±1.0/min; p<0.0001 respectively). In the presence of HS the HGE-induced changes (ΔMAP= 11.5±1.0mmHg; ΔHR= 3.3±1.0/min) were significantly decreased compared to its absence (ΔMAP=21.4±1.2mmHg; ΔHR= 12.8±2.0/min; P<0.0001 respectively). The CPT and HGE -induced increases in BP and HR suggest Sympathetic nervous system activation. These increases were significantly dampened by HS suggesting, indirectly, that its hypotensive effect may be due to an attenuation of the discharge of the sympathetic nervous system.Keywords: Hibiscus sabdariffa, Cold pesssor test, Hand grip exercise, Blood pressure, Heart rat

Effect of Mobile Phone Radiofrequency Electromagnetic Fields on Cardiovascular Parameters in Apparently Healthy Individuals

Summary: Since cell phones emit radiofrequency electromagnetic fields (EMFs), this study tested the hypothesis that cell phones placed near the heart may interfere with the electrical rhythm of the heart or affect the blood pressure. Following informed consent, eighteen randomly selected apparently healthy male volunteers aged 21.44 ± 0.53 years had their blood pressure, pulse rates and ECG measured before and after acute exposure to a cell phone. The ECG parameters obtained were: heart rate (HR), QRS complex duration (QRS), PR interval (PR) and Corrected QT interval (QTc). Results are presented as mean ± SEM. Statistical analyses were done using two-tailed paired t test for blood pressure and pulse rate data and one way ANOVA with a post hoc Tukey test for the ECG data. P<0.05 was considered statistically significant. The blood pressure and pulse rates before and after exposure to the cell phone showed no significant difference. The ECG parameters (HR: beats/min, QRS:ms, PR:ms and QTc respectively) did not differ before (66.33 ± 2.50, 91.78 ± 1.36, 151.67 ± 5.39 and 395.44 ± 4.96), during (66.33 ± 2.40, 91.11 ± 1.61, 153.67 ± 5.06 and 394.33 ± 4.05) and after calls (67.22 ± 2.77, 91.11 ± 1.67, 157.44 ± 4.46 and 396.56 ± 4.93) compared to baseline (67.17 ± 2.19, 94.33 ± 1.57, 150.56 ± 4.93 and 399.56 ± 3.88). These results suggest that acute exposure to EMFs from cell phones placed near the heart may not interfere with the electrical activity of the heart or blood pressure in healthy individuals.Keywords: Cell phone radio waves, Blood pressure, Electrocardiogramme

Ascorbic acid does not prevent sickle cell dehydration induced by calcium-activated pottasium

No Abstract.Nigerian Quarterly Journal of Hospital Medicine Vol. 11(1-4) 2001: 39-4

Attenuation of salt-induced hypertension by aqueous calyx extract of Hibiscus sabdariffa

Summary: The aqueous calyx extract of Hibiscus sabdariffa (HS) has a folk reputation as an antihypertensive agent. On account of its antioxidant properties and probably high K+ concentration, we hypothesized that HS may attenuate the development of salt-induced hypertension. Sprague-Dawley rats (n=8 each) were treated for 12 weeks as follows: control (normal diet + water), salt-loaded (8% salt diet + water), HS (normal diet + 6mg/ml HS), salt+HS (8% salt diet + 6mg/ml HS) and furosemide (normal diet+ 0.25mg/Kg furosemide). Their blood pressure and heart rates were measured and responses to noradrenalin and acetylcholine (0.01mg/kg respectively) were estimated. The cationic concentration of 6mg/ml HS was determined. The Na+ and K+ concentrations of 6mg/ml HS were 3.6 and 840mmol/l respectively. The mean arterial pressure  (MAP±SEM; mmHg) of salt loaded rats (184.6±29.8) was significantly higher than control (113.2±3.0; P<0.05), HS (90.0±7.4; P<0.001) salt+HS (119.4±8.9; P<0.05) and furosemide (94.9±11.5; P<0.01). The MAP of salt+HS and control rats did not differ significantly and the effect of HS was comparable to furosemide. The pressor response to noradrenalin or vasodilator response to acetylcholine remained similar in all groups. These results suggest that HS attenuated the development of salt-induced  hypertension and this attenuation may be associated with its high K+ content or high potassium: sodium ratio and not with altered  pressor/depressor response to noradrenalin or acetylcholine. Also the effects of HS and furosemide on blood pressure are comparable.Keywords: Hibiscus sabdariffa calyx, salt-induced hypertension, anti-hypertensive effect, High dietary K+, K+:Na

Peak expiratory flow rate in normal Hausa-Fulani children and adolescents of Northern Nigeria

Background: Peak expiratory flow rate (PEFR) is a useful parameter for assessing respiratory function in health and disease. However there are few studies reporting normal values of this parameter in Northern Nigeria in general and the North western zone in particular. Also prediction formulae for predicting PEFR from anthropometric parameters are not available for this population. The present study was therefore designed to measure Peak expiratory flow rate (PEFR) in normal Hausa-Fulani children and adolescents in Sokoto and to derive prediction formulae for this population. Methods: Apparently healthy boys (n=376) and girls (n=240) aged between 6 and 18 years were randomly selected and their height, weight and chest circumference determined. PEFR was measured at ambient temperature and pressure saturated with water vapour (ATPS) in the erect position. Regression analyses were carried out on the relationship between PEFR and each anthropometric parameter and prediction formulae with the least standard error of estimates chosen. Data obtained in this study were also subjected to prediction formulae derived from Nigerian populations elsewhere. Results: PEFR (L/min) was significantly (

Influence of antioxidant vitamins supplementation on blood glucose levels and body wastages of alloxan-induced diabetic rats

There is increasing evidence that in certain pathology states, the increased production and/or ineffective scavenging of reactive oxygen species (ROS) may play a critical role. Therefore, it seems reasonable that antioxidants can play an important role in the management of these diseases. In the current study, antioxidant vitamins A, C and E were supplemented in alloxan-induced diabetic rats for a period of 28 days. Blood glucose level was assayed by the method of Trinder (1969) and digital bench weigh balance was used to measure the weights. Final blood glucose concentrations were 4.16 ± 0.18 mmo/L in control, 5.94 ± 0.21 mmol/L in diabetic treated not supplemented and 4.56 ± 0.61 mmol/L in diabetic rats supplemented with vitamins. There were statistically significance deference,(P<0.05) between the supplemented and unsupplemented. Finally body weights were 157.57 ± 4.16 g in controls, 143.43 ± 8.70 g in diabetic not supplemented and 187.29±4.30 g in diabetic rats supplemented with vitamins. There were statistically significance difference between the supplemented and unsupplemented groups (P< 0.05). These findings suggest, in addition to oral hypoglycaemic agents, supplementation with antioxidant vitamins may improve glycaemic control and alleviates body wastage in alloxan-induced diabetic rats.Keywords: Diabetes, Vitamins, Blood Glucose, Body Weigh

Water purification properties, Cardiovascular and metabolic effects of potash alum (Trona)

Nigerian Quarterly Journal of Hospital Medicine Vol.10(2) 2000: 132-13