Opposite effect of methionine-supplemented diet, a model of hyperhomocysteinemia, on plasma and liver antioxidant status in normotensive and spontaneously hypertensive rats.

Robin S, Courderot-Masuyer C, Nicod L, Jacqueson A, Richert L, Berthelot A.

Laboratoire de Physiologie, Pharmacologie et Nutrition Preventive Experimentale, Besancon, France. ROBINRobinsophie aol.com

Hyperhomocysteinemia is often associated with an increase in blood pressure. However our previous study has shown that methionine supplementation induced an increase in blood pressure in Wistar-Kyoto (WKY) rats and a decrease in blood pressure in spontaneously hypertensive rats (SHR) with significant differences in plasma homocysteine (Hcy) metabolites levels. Previously liver antioxidant status has been shown to be decreased in SHR compared to WKY rats. It has been suggested that oxidative stress may predispose to a decrease in NO bioavailability and induce the flux of Hcy through the liver transsulfuration pathway. Thus the aim of this study was 1) to investigate the effect of methionine supplementation on NO-derived metabolites in plasma and urine 2) to investigate whether abnormalities in Hcy metabolism may be responsible for the discrepancies observed between WKY rats and SHR concerning blood pressure and 3) to investigate whether a methionine-enriched diet, differently modified plasma and liver antioxidant status in WKY rats an SHR. We conclude that the increase in blood pressure in WKY rats is related to high plasma cysteine levels and is not due to a decrease in NO bioavailability and that the decrease in blood pressure in SHR is associated with high plasma GSH levels after methionine supplementation. So GSH synthesis appears to be stimulated by liver oxidative stress and GSH is redistributed into blood in SHR. So the great GSH synthesis can be rationalized as an autocorrective response that leads to a decreased blood pressure in SHR.

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Effects of physical activity on blood pressure monitoring and morphometric parameters of the left ventricle and of the abdominal aorta in healthy elderly subjects.

Macchi C, Lova RM, Giannelli F, Papucci M, Conti AA, Paternostro F, Contini M, Miniati B, Gulisano M, Catini C.

Don Gnocchi Foundation, Florence, Italy.

To investigate the effects of physical activity not only on morphometric left ventricular parameters, but also on the abdominal aorta diameter and on blood pressure, we enrolled 100 healthy subjects, 50 males and 50 females, aged between 63 and 91 years (mean 73.3 +/- s.d. 7.7), each divided into two subgroups, sedentary and non sedentary, come to our observation for a diagnostic screening. For each subject an Echography was performed, by using an Acuson 128XP10 apparatus, equipped with a 2 MHz phased array probe, both for the study of the heart and for the study of the abdominal aorta. Then, all the subjects underwent 24 hours blood pressure monitoring by using a P6 Delmar apparatus in order to get mean systolic and diastolic blood pressure. Diastolic blood pressure was significantly related to physical activity (sedentary > non sedentary, P < 0.01), while systolic blood pressure was not; left ventricle and abdominal aorta diameters were both significantly related to sex (males > females, P < 0.001), but left ventricle diameter was significantly related to diastolic blood pressure (P < 0.01), while abdominal aorta diameter was significantly related to systolic blood pressure (P < 0.001). Our data suggest that physical activity might be strongly recommended to control blood pressure.

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Effects of atracurium on intraocular pressure, eye position, and blood pressure in eucapnic and hypocapnic isoflurane-anesthetized dogs.

McMurphy RM, Davidson HJ, Hodgson DS.

Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.

OBJECTIVE: To determine effects of atracurium on intraocular pressure (IOP), eye position, and arterial blood pressure in eucapnic and hypocapnic dogs anesthetized with isoflurane. ANIMALS: 16 dogs. PROCEDURE: Ventilation during anesthesia was controlled to maintain Paco2 at 38 to 44 mm Hg in group- I dogs (n = 8) and 26 to 32 mm Hg in group-II dogs (8). Baseline measurements for IOP, systolic, diastolic, and mean arterial blood pressure, central venous pressure (CVP), and heart rate (HR) were recorded. Responses to peroneal nerve stimulation were monitored by use of a force-displacement transducer. Atracurium (0.2 mg/kg) was administered i.v. and measurements were repeated at 1, 2, 3, and 5 minutes and at 5-minute intervals thereafter for 60 minutes. RESULTS: Atracurium did not affect IOP, HR, or CVP Group II had higher CVP than group I, but IOP was not different. There was no immediate effect of atracurium on arterial blood pressure. Arterial blood pressure increased gradually over time in both groups. Thirty seconds after administration of atracurium, the eye rotated from a ventromedial position to a central position and remained centrally positioned until 100% recovery of a train-of-four twitch response. The time to 100% recovery was 53.1 +/- 5.3 minutes for group I and 46.3 +/- 9.2 minutes for group II. CONCLUSIONS AND CLINICAL RELEVANCE: Atracurium did not affect IOP or arterial blood pressure in isoflurane-anesthetized dogs. Hyperventilation did not affect IOP or the duration of effect of atracurium.

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Blood pressure assessment in healthy cats and cats with hypertensive retinopathy.

Sansom J, Rogers K, Wood JL.

Ophthalmology Unit, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU, England.

OBJECTIVE: To determine whether there was an association between hypertensive retinopathy and high systolic, diastolic, and mean arterial blood pressures in cats. ANIMALS: 181 cats. PROCEDURE: Systolic, diastolic, and mean arterial blood pressures were measured by use of a noninvasive oscillometric technique. The range of blood pressure measurements in healthy cats from various age groups was determined. Associations among systolic, diastolic, and mean arterial blood pressure; hypertensive retinopathy; hyperthyroidism; left ventricular cardiac hypertrophy; chronic renal failure; and serum biochemical abnormalities were determined. RESULTS: All blood pressure measurements increased with age in healthy cats. The frequency of hypertensive retinopathy also increased with age and with blood pressure, and hypertensive retinopathy was particularly found in cats with systolic blood pressures > 168 mm Hg. There was an increased risk for hypertensive retinopathy in cats that were female, > 10 years old, and neutered. The risk of chronic renal failure also increased as blood pressure, particularly systolic blood pressure, increased. CONCLUSIONS AND CLINICAL RELEVANCE: Hypertensive retinopathy was common in cats > or = 10 years of age and was associated with systolic blood pressures > 168 mm Hg when measured by the noninvasive oscillometric technique.

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Systolic blood pressure diurnal variation is not a predictor of renal target organ damage in kidney transplant recipients.

Haydar AA, Covic A, Agharazii M, Jayawardene S, Taylor J, Goldsmith DJ.

Renal and Transplantation Unit, Guy's Hospital, London, UK.

Elevated blood pressure and diurnal blood pressure variation detected by ambulatory blood pressure monitoring has been shown to be predictive of worse outcome in end-stage renal disease patients in small studies. What has been lacking is a large study to determine whether these ambulatory blood pressure monitoring (ABPM)-derived variables are predictors of worse outcome in renal transplant recipients. All the patients that underwent renal transplantation and follow up at this institution from January 1998 till October 2002 were involved in this study (n=177). All patients were followed up for at least 48 weeks. Last creatinine correlated positively with duration of dialysis (p=0.035, r=0.158), kidney-donor age (p<0.0001, r=0.377), early kidney function (p<0.0001, r=0.610, r=0.683), 24-h systolic blood pressure (SBP) load (p=0.002, r=0.228), and ABPM-derived pulse pressure (p<0.0001, r=0.269). However neither office blood pressure nor SBP diurnal variation were predictors of kidney outcome. Regression analysis showed that early kidney function was the only independent predictor of transplant outcome (p<0.0001). Systolic blood pressure diurnal variation, though an important predictor of target organ damage in chronic kidney disease patients, was not a predictor of renal transplant function in renal transplant recipients. Only early kidney function was an independent predictor of later serum creatinine.

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Cardiac hypertrophy in hypertension: relation to 24-h blood pressure profile and arterial stiffness.

Lekakis JP, Zakopoulos NA, Protogerou AD, Kotsis VT, Papaioannou TG, Stamatelopoulos KS, Tsitsiricos MD, Pitiriga VCh, Papamichael CM, Toumanides ST, Mavrikakis ME.

Department of Clinical Therapeutics, Alexandra University Hospital, 12 Iridanou Street, 11528 Athens, Greece. lekakis tellas.gr

BACKGROUND: In subjects with essential hypertension peripheral blood pressure profile contributes to the pathogenesis of left ventricular hypertrophy. It is not known if central arterial pressure is superior to peripheral blood pressure profile for predicting left ventricular hypertrophy. In the present study 24-h blood pressure profile and central hemodynamics were examined to evaluate mechanical loading factors as determinants of cardiac hypertrophy in mild to moderate untreated essential hypertension. METHODS: Forty-eight untreated subjects with mild to moderate essential hypertension were examined by echocardiography for evaluation of left ventricular mass, 24-h ambulatory blood pressure monitoring (ABPM), and applanation tonometry of the radial artery with pulse wave analysis for evaluation of central hemodynamics. RESULTS: Left ventricular mass showed a statistically significant correlation with age, clinic systolic blood pressure, mean heart rate and heart rate variability during 24-h ABPM, augmentation pressure and index and central systolic blood pressure. In a multiple regression analysis including clinic systolic blood pressure, central systolic pressure, mean systolic pressure and pulse pressure during ambulatory monitoring as well as age, independent predictors of left ventricular mass were only age (P=0.006) and central systolic blood pressure (P=0.04). In conclusion, pulse wave analysis is a valuable method in predicting cardiac hypertrophy in untreated mild to moderate essential hypertension. Central systolic blood pressure should be taken into account for planning therapeutic strategies for prevention of left ventricular hypertrophy in hypertensive patients. Copyright 2003 Elsevier Ireland Ltd.

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Genome scan linkage results for longitudinal systolic blood pressure phenotypes in subjects from the Framingham Heart Study.

James K, Weitzel LR, Engelman CD, Zerbe G, Norris JM; Framingham Heart Study.

Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, Colorado, USA. Kathy.James uchsc.edu

The relationship between elevated blood pressure and cardiovascular and cerebrovascular disease risk is well accepted. Both systolic and diastolic hypertension are associated with this risk increase, but systolic blood pressure appears to be a more important determinant of cardiovascular risk than diastolic blood pressure. Subjects for this study are derived from the Framingham Heart Study data set. Each subject had five records of clinical data of which systolic blood pressure, age, height, gender, weight, and hypertension treatment were selected to characterize the phenotype in this analysis.We modeled systolic blood pressure as a function of age using a mixed modeling methodology that enabled us to characterize the phenotype for each individual as the individual's deviation from the population average rate of change in systolic blood pressure for each year of age while controlling for gender, body mass index, and hypertension treatment. Significant (p = 0.00002) evidence for linkage was found between this normalized phenotype and a region on chromosome 1. Similar linkage results were obtained when we estimated the phenotype while excluding values obtained during hypertension treatment. The use of linear mixed models to define phenotypes is a methodology that allows for the adjustment of the main factor by covariates. Future work should be done in the area of combining this phenotype estimation directly with the linkage analysis so that the error in estimating the phenotype can be properly incorporated into the genetic analysis, which, at present, assumes that the phenotype is measured (or estimated) without error.

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Transient adrenocortical insufficiency of prematurity and systemic hypotension in very low birthweight infants.

Ng PC, Lee CH, Lam CW, Ma KC, Fok TF, Chan IH, Wong E.

Department of Paediatrics, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, NT. pakcheungng cuhk.edu.hk

OBJECTIVES: A proportion of preterm, very low birthweight (VLBW, < 1500 g) infants may show inadequate adrenal response to stress in the immediate postnatal period. The human corticotrophin releasing hormone (hCRH) stimulation test was used to: (a) determine the relation between pituitary-adrenal response and systemic blood pressure in these infants; (b) characterise the endocrinological features of transient adrenocortical insufficiency of prematurity (TAP). STUDY DESIGN: A total of 226 hCRH tests were performed on 137 VLBW infants on day 7 and 14 of life in a tertiary neonatal centre. RESULTS: Basal, peak, and incremental rise in serum cortisol (Delta Cort(0-30)) on day 7 were associated significantly with the lowest systolic, mean, and diastolic blood pressures recorded during the first two weeks of life (r > 0.25, p < 0.005). These cortisol concentrations also correlated significantly but negatively with the maximum and total cumulative dose of dopamine (r > -0.22, p < 0.02), dobutamine (r > -0.18, p < 0.04), and adrenaline (r > -0.26, p < 0.004), total volume of crystalloid (r > -0.22, p < 0.02), and duration of inotrope treatment (r > -0.25, p < 0.006). Multivariate regression analysis of significant factors showed that the lowest systolic, mean, and diastolic blood pressures remained independently associated with serum cortisol (basal, peak, and Delta Cort(0-30)) on day 7. Hypotensive infants requiring inotropes (group 2) were significantly less mature and more sick than infants with normal blood pressure (group 1). The areas under the ACTH response curves were significantly greater in group 2 than in group 1, on both day 7 (p = 0.004) and day 14 (p = 0.004). In contrast, the area under the cortisol response curve was significantly greater in group 1 than in group 2 on day 7 (p = 0.001), but there was no significant difference between the two groups on day 14. In addition, serum cortisol at the 50th centile in hypotensive infants had high specificity and positive predictive value (0.80-0.93 and 0.81-0.89 respectively) for predicting early neonatal hypotension. CONCLUSIONS: This study characterises the fundamental endocrinological features of TAP: normal or exaggerated pituitary response; adrenocortical insufficiency; good recovery of adrenal function by day 14 of postnatal life. The results also provide the centiles of serum cortisol for hypotensive patients and infants with normal blood pressure, and show a significant relation between serum cortisol and blood pressure in VLBW infants.

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