摘要:

ObjectiveTo determine concordance for hypertension in adult male twins and to examine individual environmental factors associated with the manifestation of the disease in one member but not both members of a twin pair.MethodsThe subjects were 1003 monozygotic and 858 dizygotic Caucasian, male, World War II veteran twins born in the USA between 1917 and 1927, who were aged 56–66 years when surveyed by the National Heart, Lung, and Blood Institute for health behaviors and cardiovascular disease status. Hypertensive status was determined by the subjects' diagnostic reports from physicians and the subjects' past or current use of antihypertensive medications. Self-reports were validated in a subsample of 675 individual twins who were participants in a series of cardiovascular examinations and for whom blood pressure measurements were available.ResultsThe data analyses indicate that in this cohort of adult male twins, 62% of monozygotic and 48% of dizygotic cotwins of the hypertensive twins were hypertensives, compared with a prevalence of 36% in the whole cohort. Among the 281 monozygotic twins discordant for hypertension, hypertensive twins differed significantly from their non-hypertensive cotwins in the weight gain throughout adulthood and in alcohol consumption. They did not differ in weight at induction into the military, or according to smoking, physical activity or demographics. Those pairs that were concordant for hypertension gained significantly more weight throughout adulthood, consumed more alcohol, and were physically less active than concordant-negative pairs.ConclusionsThe findings from this study suggest that although genetic factors influence the development of hypertension, non-genetic and potentially modifiable lifestyle behaviors, including adult weight gain, alcohol consumption and physical activity, are closely related to the clinical manifestation of the disease.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo study membrane viscosity in various rat strains with genetic forms of experimental hypertension.DesignThe relationship between blood pressure and membrane dynamics was investigated in erythrocytes from three different rat strains with experimental hypertension, namely two models of salt-induced hypertension (Sabra and Dahl rats) and Lyon hypertensive rats with spontaneous hypertension.MethodsMembrane microviscosity was evaluated by diphenylhexatriene and trimethylamino-diphenylhexatriene fluorescence steady-state anisotropy.ResultsThere were no significant differences among particular experimental groups in trimethylamino-diphenylhexatriene anisotropy that reflect micro-viscosity changes at the water-lipid interface of the external membrane leaflet. In contrast, the diphenylhexatriene anisotropy, which is related to the core membrane microviscosity, was significantly reduced in the Dahl salt-sensitive rats (irrespective of salt intake level) and in the Sabra hypertension-prone rats with developed salt hypertension. Erythrocyte membranes of Lyon hypertensive rats also had lower values of diphenylhexatriene anisotropy than the respective normotensive controls but this difference was not statistically significant.ConclusionsSystolic (and often also diastolic) blood pressure correlated negatively with the diphenylhexatriene anisotropy in each of the three strains studied, whereas the trimethylamino-diphenylhexatriene anisotropy of the erythrocyte membranes had no significant relationship to the blood pressure. Further experiments should clarify whether the observed relationship of the diphenylhexatriene anisotropy to blood pressure reflects true pathogenetic mechanisms or is a consequence of haemodynamic changes.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveA pathogenetic role of altered α2-adrenoceptors in essential hypertension has been suggested, based on studies in humans and animals. To examine the role of the α2-adrenoceptor in genetically hypertensive rats, we compared the α2-adrenoceptor genes of stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats by restriction fragment length polymorphism analysis using human α2-adrenoceptor probes (α2-C10) andDdeI restriction endonuclease, and conducted a genetic cosegregation study.MethodFive female WKY rats were bred with five male SHRSP. Eight pairs of F1rats were mated in brother-sister pairs to yield an F2population of 84 rats. Systolic blood pressure was determined by tail-cuff sphygmomanometry. Direct arterial blood pressure was taken under ether anaesthesia just before the rats were killed. Southern blots were performed using α2C10 as a probe and the DMA from the F2generation.ResultsA restriction fragment length polymorphism of the SHRSP allele of a 1.6-kb fragment and a WKY rat allele of a 0.9-kb fragment with a common band of 1.3 kb in SHRSP and WKY rats was found, as reported previously. The distribution of the genotype based on restriction fragment length polymorphism conformed to a 1:2:1 ratio in F2rats, as expected for a Mendelian trait. There was no significant difference in the blood pressure of F2rats with respect to α2-adrenoceptor genotype.ConclusionThis study demonstrated that the α2-adrenoceptor gene restriction fragment length polymorphism distribution is a Mendelian trait in the F2rats of crossed SHRSP and WKY rats, but failed to show genetic cosegregation of this restriction fragment length polymorphism with blood pressure in this generation.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo determine whether renal interleukin-6 was produced constitutively under the normal physiological conditions and to evaluate the influence of hypertension development on interleukin-6 production in two different hypertensive models, the spontaneously hypertensive rat (SHR) and the two-kidney, one clip (2-K, 1C) hypertensive rat.DesignIn a chronic study, Wistar rats and SHR, aged 4, 5, 7 and 9 weeks, and 2-K, 1C Goldblatt hypertensive rats, at 2 and 4 weeks after applying the clip, were anaesthetized, their blood pressures were measured and the kidneys were collected and renal interleukin-6 production estimated.MethodThe rats were lightly anaesthetized with halothane and prepared for blood pressure measurement via a carotid artery cannula. Interleukin-6 production was estimated from the interleukin-6 messenger RNA (mRNA) present in the kidney tissue. The mRNA species (interleukin-6, β-actin and renin) were measured by densitometric analysis of the autoradiographs following Northern blot hybridization.ResultsThe blood pressure was approximately 100 mmHg at all ages in the Wistar rats, but rose from 101 ± 3 mmHg at age 4 weeks to 154 ± 2 mmHg at age 9 weeks in the SHR (means ± SEM,P<0.01). Constitutive production of renal interleukin-6 could not be detected in either the Wistar rats or the SHR. In 2-K, 1C rats the blood pressure was increased significantly at 2 and 4 weeks after clipping to 129 ± 3 and 140 ± 4 mmHg (means ± SEM, bothP<0.01), respectively, and the renal renin mRNA concentration was increased significantly in the clipped and decreased in the non-clipped kidneys at 2 and 4 weeks after clipping. The renal interleukin-6 mRNA could not be measured in either clipped or non-clipped kidneys at either 2 or 4 weeks after clipping.ConclusionThese findings demonstrate that renal interleukin-6 was not produced constitutively under normal physiological conditions. Moreover, in spite of the development of hypertension from two causes, genetic and renin-dependent, renal interleukin-6 was not expressed even though there is a deficit in immunological function in the SHR and damage to the renal tissue of the 2-K, 1C rats.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectivesTo compare DNA synthesis in isolated arteries of normotensive and hypertensive rats and to evaluate whether removal of the endothelium affects this process.DesignCarotid and renal artery segments were isolated from normotensive Wistar, Wistar-Kyoto (WKY) and Sprague-Dawley rats, and from spontaneously hypertensive rats (SHR), transgenic Sprague-Dawley rats harbouring the mouseRen-2 gene and from WKY rats rendered hypertensive by aortic coarctation.MethodsArtery segments were exposedin vitroto serum with or without previous gentle removal of the endothelium. Nuclear incorporation of the thymidine analogue 5-bromo-2‘-deoxyuridine was visualized by immunocytochemistry and the percentage of labelled medial nuclei was determined.ResultsIn both types of artery, obtained from 6-week-old WKY rats and from 6-week-old SHR, removal of endothelium increased the percentage of 5-bromo-2‘-deoxyuridine-labelled medial nuclei (L%). Also, in the arteries of 20-week-old Wistar rats, WKY rats and WKY rats rendered hypertensive by aortic coarctation and in vessels of 11-week-old Sprague-Dawley rats and Sprague-Dawley rats harbouring the mouseRen-2 gene, removal of endothelium increased L%. Conversely, in the arteries of 20-week-old SHR removal of the endothelium did not alter L%. Furthermore, maximally stimulated DNA synthesis was considerably smaller in de-endothelialized arteries of adult SHR than in denuded vessels from the other strains and models.ConclusionThese findings confirm that the endothelium can reduce DNA synthesis in the intact rat arterial smooth muscle. This effect is not modified by hypertension, but is selectively reduced in the arteries of adult SHR.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo study the possible involvement of intrarenal endothelial dysfunction in the modulation of the pressure-natriuresis curve in spontaneously hypertensive rats (SHR).Methods: Weexamined the effect of endothelin on pressure natriuresis in isolated perfused kidneys from 16-week-old SHR and Wistar-Kyoto (WKY) rats. Plasma and urinary endothelin levels in intact rats and the rate of endothelin release from isolated kidneys were also determined.ResultsUrinary sodium excretion by SHR kidneys was 60% less than by WKY rat kidneys at a given perfusion pressure. Endothelin-1 increased the renal vascular resistance dose-dependently and the change was comparable in SHR and WKY rats. A high perfusate concentration of endothelin-1 markedly reduced urinary sodium excretion, resulting in a significant rightwards shift of the pressure-natriuresis curve. However, endothelin-1 at concentrations below 0.1 nmol/l did not decrease urinary sodium excretion, despite its renal vasoconstrictory activity. In a differentin vivostudy, plasma endothelin-like immunoreactivity was similar in the two groups, as was the urinary endothelin excretion. However, the rate of endothelin release from isolated SHR kidneys was slightly greater than from WKY rat kidneys.ConclusionSince the difference in endothelin levels is not remarkable, it seems unlikely that increased intrarenal production of endothelin plays a role in the maintenance of hypertension in SHR by modulating the pressure-natriuresis curve.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo investigate the influence of hypertension and ageing on thein vivoeffect of acetylcholine on blood pressure and regional vascular conductance and the inhibitory effect ofNG-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthesis, on the effects of acetylcholine.MethodsMale spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats aged 3–4, 7–8 and 20–26 months, were anaesthetized with pentobarbital. After sino-aortic denervation, regional blood flow in the left common carotid, superior mesenteric, right renal and right femoral arteries was measured with pulsed Doppler flowmeters. After pretreatment with indomethacin (2 mg/kg intravenously), bolus injections of acetylcholine (0.03, 0.1 and 0.3 μg/kg intravenously) were given with or without L-NMMA (20 mg/kg intravenously).ResultsDose-dependent hypotensive responses to acetylcholine were significantly smaller in SHR than in WKY rats in each age group. Ageing reduced the hypotensive effect of acetylcholine in both SHR and WKY rats. In rats aged 3–4 and 7–8 months acetylcholine-induced increases in regional vascular conductances were significantly smaller in SHR than in WKY rats. Ageing reduced acetylcholine-induced increases in regional vascular conductances in WKY rats. L-NMMA had little effect on the responses to acetylcholine in both SHR and WKY rats. Sodium nitroprusside had similar effects in SHR and WKY rats and in age groups within each strain.ConclusionThein vivovasodilatory action of acetylcholine, which appeared to be partly independent of nitric oxide, was impaired by hypertension and age.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ObjectiveTo seek in hypertensive patients rhythmic variations of the systolic blood pressure signal obtained by ambulatory blood pressure monitoring of any inherent cycle of intermediate value between 1 and 24 h.DesignSubjects (62 hypertensive, 39 normotensive) were evaluated by 24-h ambulatory blood pressure monitoring. The hypertensive group consisted of 48 patients with essential hypertension, nine with renovascular hypertension and five with phaeochromocytoma. The groups were matched for age and weight.MethodsThe ambulatory systolic blood pressure recording served as the input for a filtering procedure that rejected unacceptable values according to predetermined criteria. The whole-day systolic blood pressure series thus obtained were subjected to Fourier analysis to obtain a spectral analysis of daily systolic blood pressure fluctuations. Daily (first 12 h), nightly (second 12 h) and whole-day average systolic blood pressure values were calculated and compared for the various groups.ResultsThe average nocturnal systolic blood pressure was found to be lower than its daily counterpart in the normal subjects and in the patients with essential hypertension, whereas in the patients with renovascular hypertension or phaeochromocytoma no such nocturnal decrease was found. The power spectrum of patients with phaeochromocytoma was statistically different from that of other aetiologies of hypertension. This was achieved due mainly to a statistically significant difference in the power spectrum integral over the low-frequency band (0–0.2 cycles/h) of the power spectrum of the 24-h systolic blood pressure signal. Resection of the phaeochromocytoma normalized the power spectrum as found by analysis of the postoperative ambulatory blood pressure monitoring data in two patients who underwent a repeat recording.ConclusionsThe technique described enables the discrimination of patients with phaeochromocytoma as a cause of hypertension from other aetiologies of hypertension. Patients with renovascular hypertension could not be distinguished from those with essential hypertension on the basis of their power spectrum. However, this technique may prove to be a valuable modality for characterizing hypertensive patients of different aetiologies.

ISSN:0263-6352    

出版商:OVID    

年代:1994

数据来源: OVID