Salt-sensitivity in normotensive and hypertensive Nigerians.

BACKGROUND: Salt-sensitivity increases the risk for the development of high blood pressure in susceptible persons and also increases the risk for cardiovascular events and mortality. OBJECTIVE: The study is to determine the pattern of salt-sensitivity among normotensive and hypertensive Nigerians. METHODS: Twenty-eight (28) hypertensive subjects (HT) and twenty-five (25) age-matched normotensive controls (NT) were given 200 mmol/day salt as sodium chloride for 5 days after control parameters had been determined. Subjects were regarded as salt-sensitive when change in mean arterial blood pressure (cMABP) between baseline levels and that after salt loading was > or = 5 mmHg. RESULTS: Systolic blood pressure and mean arterial blood pressure but not diastolic blood pressure rose significantly (p < 0.05 and p < 0.001 respectively) in NT subjects while all the parameters showed significant increases in hypertensive subjects (SBP p < 0.01; DBP p < 0.001; MABP p < 0.0001). More hypertensive subjects (60.7%) were salt-sensitive compared with normotensive (52.0%) subjects (p < 0.05). CONCLUSION: This study has demonstrated pressor responses to acute salt-loading in normotensive and hypertensive Nigerians and salt-sensitivity was higher in hypertensive subjects.

Oral toxicity studies of a Nigerian polyherbal health tonic tea extract in rats.

In the present study, acute and subchronic oral toxicity studies of an aqueous extract of a Nigerian Polyherbal Health Tonic (PHT) were investigated in adult Wistar rats of both sexes and weighing between 110-200 g. Acute toxicity study was conducted using limit dose test of Up and Down Procedure under computer guided statistical software program (AOT 425 StatPgm). The subchronic toxicity was evaluated in 4 groups of rats made up of six rats/group, administered single, daily oral doses of 10 ml/kg distilled water (DW), 125, 500 and 1500 mg/kg of PHT, respectively, for 90 days. On the 91st day, blood samples for haematological and biochemical assays were collected through cardiac puncture and selected vital organs harvested en bloc for histopathological examination under inhaled anaesthesia. Results showed PHT to be relatively safe on acute toxicity with an estimated LD50 value greater than 5000 mg/kg/oral route. On prolonged exposure, PHT induced initial weight gain in the 1st 6 weeks followed by significant (P < 0.05) dose related weight loss in the latter 6 weeks. The extract also caused significant (P < 0.05) dose related elevation of the full blood count parameters, dose unrelated elevation of serum urea, liver enzymes, serum proteins, albumin, total and conjugated bilirubin. On histology, PHT induced dose dependent gastric mucosal denudation, bile ductal lining distortion, diffuse pulmonary interstitial fibrous proliferation and diffuse splenic lymphocytic proliferation. Thus, our results showed that PHT use may be relatively safe on acute exposure but toxic on chronic exposure to high doses, although reversibility of these toxic effects was not studied in the present study.

Effect of chloroquine on strips of non-pregnant and pregnant mice uteri in-vitro.

Chloroquine (CQ) remains the household drug for the treatment of malaria especially among pregnant women. However, there are reports that CQ inhibits the contractile process in non-pregnant rat's uterus. The aim of this study is to compare responses to CQ between non-pregnant and pregnant mice and identify some mechanisms involved. Experiments were carried out in non-pregnant and pregnant mice pretreated 24 hours before with 1.5 mg/kg-body weight stilboesterol given orally. Strips of uterine smooth muscle, approximately 5 mm in diameter, were mounted in a 20 ml organ bath containing De Jalon solution bubbled with a 95% O2-5% CO2 gas mixture. Responses of the strips to graded concentration of acetylcholine (ACh) (10(-9) to 10(-5) mol/L), oxytocin (OXY) (10(-5) to 10(-2) IU/ml) and CQ (10(-6) to 4 x 10(-4) mol/L) were investigated. The strips were then incubated in 4 x 10(-4) mol/L CQ for 15 mins and the cumulative dose responses for OXY were repeated. To investigate mechanism of action, the strips were incubated for 15 mins in N(w)-nitro L-arginine methyl ester (L-NAME) and the cumulative responses to CQ repeated. Each investigation was carried out in fresh tissue mounted on Grass Model FT03 force transducer coupled unto a 4-channel Grass Model 7D Polygraph. CQ (low to moderate level), ACh and OXY led to increases in contractile responses in the uteri. There were greater contractile responses in non-pregnant than pregnant mice to CQ and ACh. At high doses, CQ had an inhibitory effect on the uterine contraction. Incubating in CQ led to abolition of contractile responses to OXY and ACh. In the presence of L-NAME, inhibitory effect of CQ at high doses was attenuated in pregnant mice only. The results suggest that CQ at high doses inhibits contractile responses in non-pregnant and pregnant mice. Enhanced nitric oxide bioactivity attenuated this inhibitory effect.

Morinda lucida reduces contractility of isolated uterine smooth muscle of pregnant and non-pregnant mice.

The present work investigated the effect of Morinda lucida (M. lucida) extract on isolated uterine smooth muscle of pregnant and non-pregnant mice. Pregnant and non-pregnant mice were pretreated with oral stilboesterol (0.1 mg/kg body weight) and killed by cervical dislocation. Thin strips of the uterus were cut and mounted in a 20 ml organ bath containing De Jalon solution bubbled with 95%O2-5% CO2 gas mixture. The strips were connected to a force transducer coupled to a Grass 7D Polygraph for the recording of isometric tension. Effects of graded concentrations of oxytocin (OXY; 10-5-10-2 mol/L), acetylcholine (ACh; 10-9-10-5 mol/L) and M. lucida extract (0.015-1.5 mg/ml) were recorded. Fresh uterine strips were then incubated with M. lucida extract for 5 mins and cumulative response to OXY was repeated. Another set of fresh strips was incubated in L-NAME for 15 mins and the cumulative responses to M.lucida extract were repeated. OXY resulted in increased contractile responses in both pregnant and non-pregnant uterine muscles. M. lucida resulted in relaxation of the uterine smooth muscle in both pregnant and non-pregnant mice at all doses. However, at 1.5mg/ml, M. lucida completely blocked spontaneous uterine contractions. Following incubation with L-NAME, M. lucida extract led to a slightly greater relaxation of the uterine strips. In conclusion, M. lucida reduced contractility of uterine smooth muscle in both pregnant and non-pregnant mice as well as blocking contractile responses to OXY and Ach in uterine smooth muscle of pregnant and non-pregnant mice. There was no significant alteration of M. lucida activity by L-NAME suggesting that the action of the compound on uterine muscle is not associated with impaired nitric oxide synthase.

Effect of chronic co-administration of metformin and vitamin C on plasma glucose and lipid concentrations in normal rats.

In clinical setting, uncomplicated diabetes mellitus type 2 is managed with anti-oxidants (e.g. ascorbic acid, alpha-tocopherol, etc.) with standard oral hypoglycaemic agents, which is aimed at limiting its glucose auto-oxidation and lipid peroxidation complications. The current study is an experimental animal study aimed at investigating the effect of co-administration of metformin and ascorbic acid (Vitamin C) on plasma glucose and lipid levels in non-diabetic rats which could serve as a template for future studies in this area. The hypoglycaemic and hypolipidaemic activities of metformin, ascorbic acid, and metformin-ascorbic acid combination were studied in 4 groups consisting of 6 rats per group and weighing 120 - 155 g, by administering oral doses of 5, 10 and 15 (for co-administration) mg/kg/day of the drugs, respectively, for 30 days. The acute oral toxicity of the combination was also conducted using limit dose test of Up and Down Procedure of Acute Oral Toxicity test. Results of the study showed that metformin and metformin-ascorbic acid combination induced significant and comparable hypoglycaemia. The drug combination also lowered plasma total cholesterol, low density lipoprotein-cholesterol (LDL-c), very low density lipoprotein-cholesterol (VLDL-c) significantly but had no effect on plasma high density lipoprotein-cholesterol (HDL-c). The LD50 estimate of the drug combination was greater than 5000 mg/kg body weight/oral route. The results of this study suggest the drug combination could have hypoglycaemic and lipid-lowering effects.

Carotid chemoreceptor reflexes following dietary salt loading in rats.

There is a strong association between salt intake and hypertension. Alterations in baroreceptor activity, which precede and contribute to the elevation in blood pressure, have also been shown to affect chemoreceptor reflex response. Dietary salt loading with 8% sodium chloride was carried out in Sprague Dawley rats aged 8 weeks for a period of 5-6 weeks. Blood pressure was thereafter recorded under anaesthesia from the common carotid artery with a Grass Polygraph 7D model, whereas serum Na and K concentrations were measured using a flame photometer. Salt loading resulted in elevated arterial blood pressure as well as hypokalaemia. Stimulation of the carotid chemoreceptor by injection of sodium dithionite resulted in elevated arterial blood pressure, decreased heart rate and hyperventilation in both control and salt-loaded rats. However, the bradycardic response as estimated by the difference in percentage reduction in heart rate was significantly higher in salt rats (36%) than in the control rats (10%). The results indicate that a high-salt diet results in enhanced bradycardic response to carotid chemoreceptor stimulation and that this observation may be related to the attendant hypokalaemia.

The role of traditional birth attendants in Atakumosa, Nigeria.

All 26 traditional birth attendants (TBAs) and their 109 clients in 15 settlements in Atakumosa West Local Government Area (LGA) in Nigeria were interviewed to assess TBA training, practices and utilisation. The study showed that more than 80% of TBAs were older women with more than four children, practiced single-handedly and held other occupations. About 54% of those studied had no designated room for deliveries; twenty-one (80.8%) did not consider any pregnant woman to be at high risk; three (11.5%) perform intravaginal examinations during labour and only a few recognise complications; twelve (46.2%) never refer patients. Despite these deficiencies, TBAs continue to practise in appreciable numbers and their services continue to be on demand in the communities under study. Nearly all of the clients interviewed had started to use TBAs by the age of 25 and 50% had used TBAs for all of their deliveries. Most TBAs provide antenatal care and 77% had a case load of less than five clients per month. Ninety-six per cent of the clients had not been referred by the TBA before. Although 61% of clients felt TBAs in a future pregnancy and 49% would recommend TBA care to other women. Low socio-economic status, illiteracy, poor awareness of modern maternal health (MCH) facilities, personalized care, strong family influence and easy access to TBA services were strong factors promoting traditional midwifery in the LGA. If adequately trained, equipped, supported and supervised, TBAs can contribute towards safe motherhood in Nigeria and in other developing countries.