Effect of salt loading and gender influences on plasma atrial natriuretic peptide levels and cardiovascular parameters in normotensive and hypertensive Nigerians

Background: Prevalence of hypertension is higher among Sub-Saharan Africans than whites and there is a sex difference in the prevalence. Though, salt retention has been implicated in pathogenesis of hypertension, the basis is not completely known. Atrial natriuretic peptide (ANP) might play a role.Method: 43 apparently healthy normotensive male and female Nigerians and 37 aged-matched hypertensive counterparts were orally administered 11.6g of dietary salt each per day for 5 days. Their plasma ANP levels, heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MABP) were determined before and after salt loading.Results: Normotensive and hypertensive male and female subjects had similar basal ANP levels. However, salt loading significantly raised the ANP concentrations (p = 0.0001) in normotensive subjects but not significantly in hypertensive counterparts. ANP levels rose significantly in the normotensive males (p = 0.0024) and females (p = 0.0002) but not significantly in the hypertensive counterparts. Besides, salt significantly decreased HR in normotensive (p = 0.0095) and hypertensive (p = 0.0397) subjects but increased SBP (p < 0.01) and MABP (p< 0.01) in both study groups and DBP (p = 0.0014) in hypertensive group only. SBP, DBP and MABP were all significantly elevated (p < 0.05) in hypertensive males and females but not significantly in normotensive females.Conclusion: Although, basal ANP levels were similar in the study normotensive and hypertensive subjects, other findings in this study suggest that ANP as well as female gender could ameliorate increased blood pressure response to salt loading especially in a normotensive state.Keywords: Atrial natriuretic peptide, blood pressure, salt loading, gender, hypertensio

Chronic exposure to high environmental temperature exacerbates sodium retention and worsens the severity of salt-induced hypertension in experimental rats via angiotensin receptor activation

Background: There is paucity of information on how exposure to high environmental temperature interacts with high dietary salt to influence cardiovascular outcome in the face of global warming.Method: This study investigated the impact of high environmental temperature (HET) on the cardio- renal indices of an animal model of hypertension (fed on high salt diet, HSD), and evaluated the effectiveness of angiotensin II receptor blocker (ARB), telmisartan, in modulating these indices. Fifty-six male Sprague Dawley rats (70-90g , 7 week old) were randomly assigned into seven groups of 8 rats, which include control rats (I), fed 0.3% NaCl diet; salt loaded rats (II), fed with 8% NaCl (high salt) diet; Heat rats (III), exposed to HET (37.5-38.5oC) 4 hours daily per week; salt loaded + Heat rats (IV), fed with 8% NaCl diet and exposed to HET daily. Next, salt loaded + ARB rats (V) , fed 8% NaCl diet and treated with telmisartan (30mg/kg); Heat +ARB rats, exposed to HET and treated with telmisartan (30mg/kg); salt loaded +HET+ARB rats (VI), fed with 8% NaCl diet, exposed to HET and treated with telmisartan (30mg/kg). Experiment lasted 8 weeks. Blood Pressure and heart rate were determined invasively and electrolytes by selective ion electrode method. Data analyzed using ANOVA, with P<0.05 significant.Results: Systolic and Diastolic BP, Mean Arterial Pressure, Rate Pressures Product (RPP) (P<0.05), and plasma Na+ (P<0.05) were significantly higher with associated suppressed Na+ excretion (P<0.05) in salt loaded rats exposed to HET compared to rats fed a high salt diet alone. Telmisartan significantly attenuated the elevated blood (P<0.05) and RPP (P<0.05), in the HSD rats exposed to HET, with no corresponding reduction in the rats fed a HSD alone.Conclusion: This indicates that chronic exposure to hot environment exaggerated cardiovascular response to high salt diet possibly via angiotensin II pathway with consequent enhanced ARB action.Keywords: Angiotensin II receptor; high salt diet; hot environment; environmental temperature; heat exposure; hypertensio

Endothelium-dependent and -independent relaxations in aortic rings obtained from hypertensive hooded (Aguti) rats.

Experimental hypertension studies are few in the hooded (Aguti) rat. The present study was designed to investigate the usefulness of this rat strain for experimental hypertension studies and to test the hypothesis that the hypertension may be associated with a diminution of endothelium dependent and independent relaxations. Hypertension was induced in inbred hooded rats (n=8 each) by administering 8% salt in the diet and /or 100 mg/kg/day Nω-nitro-L-arginine-methyl-ester (LNAME) in the drinking water for six and/or four weeks respectively. The rats were anaesthetized using a 25% urethane and 1% chloralose mixture given intraperitoneally at a dose of 5mg/kg. Their blood pressure was measured invasively. Thereafter, relaxations of rat aortic preparations to acetylcholine, histamine and sodium nitroprusside (SNP) were assessed using standard organ bath conditions.

Testosterone-dependence of oxidative stress in Sprague-Dawley rats fed a high salt diet

Background: One of the mechanisms by which high salt diet (HSD) induces hypertension is by increasing the generation of reactive oxygen species (ROS). Salt sensitivity exhibits sex difference which is higher in males when compared with females. Likewise, sex disparity in oxidative stress has also been suggested. However, the role of the sex steroids in these sex differences is not clear. Therefore, experiments were designed to assess the role of testosterone on the oxidative status of male rats fed a high salt diet.Methods: Weanling male Sprague-Dawley rats were either sham-operated or orchidectomised under (90mg/kg bodyweight ketamine and 10mg/kg bodyweight xylazine i.p) anesthesia, with or without testosterone replacement (10mg/kg sustanon 250® i.m) once in 3 weeks. They were placed on a diet with normal 0.3% or high 8% NaCl content for 6 weeks. Blood pressure (BP) was measured via arterial cannulation. Levels of lipid peroxidation (LP), superoxide dismutase (SOD), bilirubin and testosterone were measured in the serum.Results: Orchidectomy attenuated the BP elevating effect of a high salt diet, but concomitant replacement of testosterone in orchdectomised rats restored the BP values towards that observed in sham-orchidectomised animal. Orchidectomy abolished while testosterone replacement re-established the significant increase (p<0.001) in LP of the HSD group when compared with the control. High salt diet significantly reduced (p<0.01) the serum levels of SOD. Orchidectomy prevented the reduction in SOD level effect of a high salt diet but testosterone replacement re-established it. Findings from this study show that orchidectomy reduced oxidative stress in male Sprague-Dawley rats fed a high salt diet suggesting a role for testosterone in ROS generating effect of a high salt diet.Keywords: Bilirubin, Hypertension, Lipid peroxidation, Orchidectomy, Oxidative stress, Super oxide dismutase, Testosteron

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 (0.1mg/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 (0.015–1.5mg/ml) were recorded. Fresh uterine strips were then incubated with M. lucida extract for 5mins and cumulativeresponse to OXY was repeated. Another set of fresh strips was incubated in L-NAME for 15mins and the cumulative responses to M.lucida extract were repeated. OXY resulted in increased contractileresponses 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 1.500mg/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. lucidareduced 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 nonpregnantmice. 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

Addendum

Re- Article” Vitamin A Supplementation as an Adjunct in the Treatment of Mild to Moderate Childhood Malaria: Effect on Haematological IndicesBy Oreagba IA et al - Nigeria Medical Practitioner Vol. 69, No. 3-4, page 32 - 38, 2016We hereby Acknowledge this Study was supported by a Research Grant from the Central Research Committee (Grant No. 2010/03; Ref No. 537177) of the University of Lagos

Retraction: Statement of Retraction: Khaki-khatibi F, Yaghoubi A.R, Rahbani N.M. “Study of antioxidant enzymes, lipid peroxidation, lipid profile and immunologic factor in coronary artery disease in East Azarbijan”

The Editors and Publisher of the International Journal of Medicine and Biomedical Research would like to inform the readers that the following article has been retracted from the journal:Khaki-khatibi F, Yaghoubi A.R, Rahbani N.M. Study of antioxidant enzymes, lipid peroxidation, lipid profile and immunologic factor in coronary artery disease in East Azarbijan. Int J Med Biomed Res 2012;1(2):147-152. doi: http://dx.doi.org/10.14194/ijmbr.1210It was found out that a substantially similar version of this article had been submitted to, and published in Journal of Cardiovascular and Thoracic Research.Fatemeh Khaki Khatibi, Alireza Yaghoubi, Nosratollah Zarghami, Mohammad Rahbani, Hossein Babaie. Evaluation of hs-CRP, antioxidant markers and MDA in patients of coronary artery disease (CAD) containing non-smokers and non-diabetics. J Cardiovasc Thorac Res 2011; Vol.2 (4):13-18.The article has been retracted upon the request of the corresponding author, Khaki-khatibi F, due to admitted plagiarism.However, this constitutes a violation of publication ethics. It is a breach of warranties made by the author with respect to originality upon which we received, peer-reviewed, accepted and published the article. To maintain scholarly record, the article will remain online; however, it would be watermarked on each page as RETRACTED. We offer apologies to our readers for not detecting this during the evaluation process

Errata: Packed Cell Volume in Rheumatoid Arthritis Patients at First Presentation

Errata: Packed Cell Volume in Rheumatoid Arthritis Patients at First PresentationOguntona A.S., Fawole A.E. and Sobowale TThe above titled paper was published in Vol 74, No 1-2, 2018, edition with some texts missing on paragraph 4 of page 14. The affected page is corrected and hereby republished in this edition

Correction

International Journal of Medicine and Biomedical ResearchVolume 5 Issue 1 January – April 2016Title: The profile of tuberculosis infection at the Babcock University Teaching HospitalPages: 1-8The title should read:“The profile of tuberculosis infections at the Babcock University Teaching Hospital”Authors’ names should also appear as:“Shobowale E.O1*, Elikwu C.J1,Olusanya A.O2, Abiodun O3” The affiliations remain the same:“’1Department of Medical Microbiology and Parasitology, Babcock University, Ogun State. 2Pathcare Laboratories, Lagos. 3Department of Community Health, Babcock University, Ogun State.”The errors are regretted.-Editor-in-Chief, IJMB