ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objectives:To analyse the association between time of onset of subarachnoid haemorrhage and diurnal blood pressure variations of ambulant normo- and hypertensive subjects.Design:Retrospective, population-based study.Setting:The population (246 000) of the Health Care District of Central Finland.Patients:During 1980-1987 a total of 332 subjects in the study population had their first subarachnoid haemorrhage. The hour of onset could be obtained for 287 patients, and these form the basis of the present study.Results:The onset of subarachnoid haemorrhage occurred significantly more often during the waking hours than during the night. The correlation between the hourly numbers of patients suffering a haemorrhage and the corresponding mean systolic and diastolic blood pressure values of ambulant normo- and hypertensive subjects was highly significant (r=0.88, P<0.001). The results were similar when the 224 patients with proved aneurysmal bleed were analysed separately (r=0.79-0.85, P< 0.001).Conclusions:The diurnal blood pressure variations of ambulant normo- and hypertensive subjects, especially the transient blood pressure peaks reaching much higher levels of pressure during the waking hours than during the night, may be crucial in determining the time of rupture of a critically weakened aneurysm wall.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:To study the influence of the adrenergic system, fasting serum insulin level and insulin sensitivity on systolic (SBP) and diastolic blood pressure (DBP) in young individuals.Design and methods:In a population survey we measured SBP and DBP (using the London School of Hygiene sphygmomanometer) and fasting levels of serum catecholamines, serum insulin and insulin sensitivity in 383 randomly recruited subjects (mean age 25.0 years) of both sexes. Insulin sensitivity was estimated from a combined intravenous glucose and tolbutamide tolerance test and calculated using Bergman's minimal model. Confounders were body mass index, waist: hip ratio, maximal aerobic capacity, age, sex, and consumptions of tobacco and alcohol.Results:In a multiple regression analysis including the above factors, the most important determinant of SBP, after sex, was the plasma adrenaline level (partial correlation coefficient, rp=0.23, P<0.01). No significant association was found between plasma noradrenaline level and SBP. A significant association was found between plasma adrenaline level and DBP in females only (rp=0.15, P<0.05). Overall, the plasma adrenaline level was more important than the plasma noradrenaline level. Fasting serum insulin level and insulin sensitivity were each significantly correlated with both SBP and DBP in univariate analyses, but not in a multiple regression analysis. A family history of hypertension was associated with higher SBP level, body mass index and fasting serum insulin level, and with lower insulin sensitivity, but with no difference in circulating plasma adrenaline or noradrenaline compared with individuals without a family history. In a multiple regression analysis with the above confounders, no significant association between SBP and plasma adrenaline level could be found in either sex for subjects with a family history of hypertension. Both male (rp=0.41, P<0.001) and female (rp=0.18, P<0.05) subjects with no history of family hypertension had a significant association between SBP and plasma adrenaline level in a multiple regression analysis.Conclusion:In young healthy Caucasians adrenergic activity is an important determinant for SBP. The importance of fasting serum insulin level and insulin sensitivity on blood pressure level is minor when confounders are considered.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:The relationship between the number of β-adrenoceptors and polyploidy in cultured aortic smooth muscle cells derived from different age groups of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were examined.Design:The number of β-adrenoceptors, the percentage of multinucleated cells and the incidence of polyploidy from cultured smooth muscle cells derived from SHR and WKY rats aged 3-4, 10-12 and 28-30 weeks were measured. The effect of passaging of the cells on the expression of β-adrenoceptors and polyploidy on cultured smooth muscle cells from both SHR and WKY rats was also investigated.Methods:Receptor binding experiments were carried out using [125]-monoiodocyanopindolol with osmotically lysed cultured aortic smooth muscle cells to investigate the properties of vascular β-adrenoceptors in SHR and WKY rats. The proportion of polyploid smooth muscle cells was determined by frequency distribution analyses of Feulgen DNA microdensitometric measurements.Results:The incidence of polyploid smooth muscle cells was consistently higher in cells cultured from SHR than in those from WKY rats in all three age groups, with a positive correlation between polyploidy and age in SHR. Furthermore, in all three age groups the number of β-adrenoceptor binding sites was also higher in cultured smooth muscle cells from SHR than in those from WKY rats. There was no significant difference in the receptor affinity. The increase in β-adrenoceptor number was associated with an increase in polyploidy, and both of these changes were positively correlated both with the age of the rats from which these cells were derived and with the number of passages.Conclusions:Under cell culture conditions the expression of P-adrenoceptor density increases with the number of passages in both SHR and WKY rats. Smooth muscle cells derived from older SHR and WKY rats have a greater propensity to develop polyploidy. This trend is significantly accelerated in cultured smooth muscle cells derived from SHR compared with those from WKY rats, suggesting a premature ageing process. These findings suggest that, in cultured smooth muscle cells from SHR and WKY rats, β-adrenoceptors may influence the expression of polyploidy.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:To investigate the effects of high dietary sodium on brain and kidney Na,K-ATPase activity in Dahl salt-sensitive (Dahl-S) and salt-resistant (Dahl-R) rats.Methods:From the age of 4 weeks Dahl-S and Dahl-R rats were fed either standard or high-sodium diet (8% sodium chloride) for 3 weeks. The hydrolysis of [Y-32P]-ATP in the absence or presence of various concentrations of ouabain was used to determine apparent Na,K-ATPase activity and its isoform composition. To assess whether reduced Na,K-ATPase activity was caused by an endogenous inhibitor, brain and kidney microsomes were pre-incubated with antibody Fab fragments (Digibind).Results:The high-sodium diet increased mean arterial pressure in the Dahl-S but not in the Dahl-R rats. Two binding sites (α1and α2) in several areas of the brain and one binding site in the kidneys (α1) were detected. The high-sodium diet reduced Na,K-ATPase activity in the hypothalamus of the Dahl-S but not of the Dahl-R rats, but did not cause changes in the brain cortex, pons or kidney. The Na,K-ATPase isoform composition in the brain cortex, hypothalamus and pons and kidney was not changed by the high-sodium diet. In the rats fed the standard-sodium diet, Digibind increased Na,K-ATPase activity only in the hypothalamus of the Dahl-S rats, in rats fed the high-sodium diet, Na,K-ATPase activity was increased by Digibind in the hypothalamus of both strains of rats, but by more in the Dahl-S rats.Conclusion:The present data indicate that a high-sodium diet inhibits hypothalamic Na,K-ATPase via increased binding of an inhibitor.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:To assess intracellular pH regulation in the presence of bicarbonate in resistance arteries from spontaneously hypertensive rats and Wistar-Kyoto (WKY) rats.Methods:Intracellular pH was determined in isolated resistance arteries from male adult SHR and WKY rats with the pH-sensitive fluorescent dye bis-carboxyethyl carboxyfluorescein, while the arteries were mounted in a myograph for simultaneous measurements of force. The arteries were acid-loaded using the ammonium chloride technique and the recovery from the acidosis was determined in resting arteries and in arteries activated with 50mmol/tassium or arginine vasopressin. This protocol was performed in the presence and in the absence of bicarbonate.Results:In the absence of bicarbonate the intracellular pH was higher in resting arteries from SHR than in those from WKY rats, whereas during activation no significant difference was found. In the presence of bicarbonate no difference in intracellular pH between arteries from SHR and WKY rats could be found. The addition and washout of 15mmol/l ammonium chloride were associated with large force transients in activated arteries both from SHR and from WKY rats. The proton recovery rate at intracellular pH6.85 in the absence of bicarbonate was higher in activated arteries from SHR than in those from WKY rats, whereas in resting arteries no significant difference was found. In the presence of bicarbonate no significant difference between SHR and WKY rat arteries was found.Conclusion:In the presence of bicarbonate a possible abnormality of the sodiumhydrogen exchange in resistance arteries from SHR is not manifested, because regulation of intracellular pH by bicarbonate-dependent mechanisms can compensate for such an abnormality.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:To investigate the effects of hypertension and diabetes mellitus on vascular albumin permeability and hypertrophy in 11-week-old Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) with and without 3 weeks of streptozotocin-induced diabetes.Methods:Vascular albumin permeability was measured as tissue content of intravenously injected Evans blue dye.Results:Diabetic rats showed hypertrophy of the kidneys, and hypertensive rats showed hypertrophy of the heart. In the mesenteric artery there was an additive hypertrophic effect of diabetes and hypertension. The Evans blue content in kidneys was higher in diabetic SHR than in diabetic and in control WKY rats. The kidney: plasma Evans blue ratio was higher in diabetic SHR than in the other three groups, and the heart:plasma Evans blue ratio was higher in diabetic SHR than in control WKY rats or control SHR. The Evans blue content and tissue: plasma Evans blue ratio did not differ in aorta, mesenteric artery or skeletal muscle among the groups. There was no positive correlation between vascular albumin permeability and hypertrophy in any of the tissues studied.Conclusions:There was no relationship between vascular albumin permeability and hypertrophy, but increased vascular albumin permeability was found in kidneys and hearts of rats with both diabetes and hypertension. This suggests an additive or synergistic effect of diabetes and hypertension in producing vascular changes.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

To determine the influence of experimental hypertension on the structure and function of porcine coronary small arteries.Methods:Miniature pigs underwent partial left renal artery constriction and contralateral nephrectomy. Blood pressures were recorded, using indwelling carotid artery catheters. After 4 weeks the pigs were killed, the heart was removed and subepicardial third-order branches of the left anterior descending artery were dissected and mounted in a myograph for morphological and functional assessment.Results:Final mean ± SEM systolic and diastolic blood pressures were, respectively, 197±9 and 142 ± 7mmHg (n=21) for the hypertensive pigs and 125 ± 4 and 80 ±4 mmHg(n=11) for the sham-operated control pigs. Hypertension was associated with significant left ventricular hypertrophy. The media thickness: lumen diameter ratio was increased significantly in hypertensive intramyocardial small arteries, caused mainly by remodelling (remodelling index 92%) rather than by medial growth. Maximal contractile responses to potassium and acetycholine were significantly depressed in the arteries from hypertensive pigs, whereas endothelium-dependent relaxation responses to bradykinin, substance P and serotonin were not significantly influenced by hypertension.Conclusions:These results demonstrate that even short-term hypertension induces both structural and functional changes in left ventricular intramyocardial small arteries.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Objective:To investigate the acute effects of the calcium antagonists nicardipine and diltiazem on blood pressure and left ventricular diastolic filling in hypertensive patients.Design:Transmitral flow velocities were measured by pulsed-Doppler echocardiography before and during infusion of nicardipine (1, 2 and 3 μg/kg per min) and diltiazem (5, 10 and 15 μg/kg per min) in seven patients with essential hypertension. Arterial pressure was measured directly, and other haemodynamic indices were obtained using a right-sided heart catheter.Results:The calcium antagonists significantly decreased blood pressure and total peripheral resistance. Changes in mean blood pressure correlated with those in total peripheral resistance. Heart rate was significantly increased by nicardipine but decreased by diltiazem. Nicardipine and diltiazem both increased significantly the peak early filling velocity and the peak velocities of early: late filling ratio. The changes in the ratio correlated inversely with those in total peripheral resistance.Conclusion:Intravenous infusion of nicardipine or diltiazem causes a fall in blood pressure by decreasing total peripheral resistance, with beneficial effects on left ventricular diastolic filling that are independent of changes in heart rate in patients with hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1995

数据来源: OVID