摘要:

Type A behavior has been associated with coronary heart disease as well as high cholesterol and smoking, major risk factors for coronary heart disease, but the data indicating a similar association with hypertension are inconsistent Since past studies have usually based hypertension on a single blood pressure assessment or have often included treated hypertensive patients, this inconsistency is not surprising. The current study compared the prevalence of Type A behavior (assessed by Rosenman's structured interview) between 109 untreated hypertensive subjects and 109 age-, sex-, ethnic-, and occupation-matched normotensive subjects. Hypertension status was based on five repeated assessments over a 5-month period. Results indicated that Type A behavior is more prevalent in untreated, mildly hypertensive employed individuals than occupationally matched normotensive subjects. Type A component analysis confirmed the importance of hostility and certain vigorous voice stylistics in predicting cardiovascular conditions. These findings, taken together with the evidence linking Type A behavior with high cholesterol and cigarette smoking, further support the view that this behavior pattern is associated with increased risk of coronary heart disease.

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In severe preeclampsia, short-term peripartum management of hypertension with hydralazine is complicated by relatively prolonged hypotensive episodes, resulting in fetal distress. We hypothesized that nitroprusside's rapid onset and brief antihypertensive action would permit more controlled blood pressure reduction. Nitroprusside was infused into 10 invasively monitored subjects until mean arterial pressure either 1) was gradually reduced 10-20% or 2) fell abruptly. Subjects fell into two groups, defined by whether the hypotensive effect of nitroprusside was accompanied by a fall in heart rate (group A, n = 1) or a rise (group B, n=2). Group B showed the expected sinoaortic baroreceptor reflex elevations in heart rate (+17 ±6 beats/min) in response to moderate falls in mean arterial pressure (‐32±9 mm Hg) elicited by moderate doses (1.03±0.23 /tg/kg/min). However in group A, steep reductions in mean arterial pressure (‐75±22 mm Hg, p<0.0001), significantly greater than in group B (p<0.05), occurred at much lower doses (0.35±0.23 /ig/kg/min;/?

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This study was performed to determine if an alteration in vascular polyamine contents is associated with the development of deoxycorticosterone acetate-salt hypertension. The effects of chronic administration of a-difluoromethylornithine, a specific irreversible inhibitor of ornithine decarboxylase and thus polyamine biosynthesis, on vascular polyamine contents, structure, and function as well as the development of hypertension was studied. Control and deoxycorticosterone acetate-salt rats received either tap water or a drinking solution containing or-difluoromethylornithine for 6 weeks, during which period systolic blood pressures were recorded. Vascular reactivity studies were performed on rings of aorta and tail artery. Medial thickness, vessel weight, and vascular polyamine contents were also assessed in these arteries. ar-Difluoromethylornithine treatment had no significant effect on either systolic blood pressure or vascular structure, function, and polyamine contents of control animals. The elevation in blood pressure and the increase in medial thickness, ring weight, and vascular polyamine contents as well as altered vascular reactivity observed in deoxycorticosterone acetate-salt rats was significantly attenuated by ar-difluoromethylornithine treatment These results are the first to demonstrate that vascular polyamine contents are elevated in the deoxycorticosterone acetate-salt rat and that chronic a-difluoromethylornithine treatment prevents the rise in vascular polyamines as well as the elevation in blood pressure and attendant changes in the vasculature. Thus, the increase in vascular polyamines may comprise a critical link between the initiating stimuli and the alterations in vascular structure and function implicated in the pathogenesis of deoxycorticosterone acetate-salt hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We measured plasma concentrations of immunoreactive endothelin-1 (irET-1) in the prehypertensive and hypertensive phases in spontaneously hypertensive rats (SHR) and in malignant hypertension caused by deoxycorticosterone acetate (DOCA) -salt administration in SHR. We also measured concentrations of this peptide in another model of malignant hypertension, the two-kidney, one clip (2K1C) renovascular hypertensive rats chronically given caffeine. Plasma irET-1 concentrations in young (6-week-old) and mature (18-week-old) SHR did not differ from those of age-matched Wistar-Kyoto (WKY) rats. Four weeks of treatment with DOCA-salt increased blood pressure, blood urea nitrogen, serum creatinine, and plasma irET-1 in SHR but not in WKY rats. Eight weeks of DOCA-salt treatment further increased these values in SHR. Plasma irET-1 concentrations were not increased in the 2K1C rats. Six weeks of caffeine administration increased blood pressure, blood urea nitrogen, serum creatinine, plasma renin activity, and plasma irET-1 in the 2K1C rats but not in the sham-operated rats. Highperformance liquid chromatographic profiles of plasma extracts pooled from these rats with malignant hypertension showed that a major component of irET-1 eluted in the position of synthetic ET-1(1-21). Furthermore, acute hypertension induced by angiotensin II or phenylephrine did not affect the plasma irET-1 concentration in rats. The results suggested that the plasma ET-1 concentration is increased in rat models of malignant hypertension and that the high blood pressure itself is not the main factor involved in the increase of plasma ET-1. {Hypertension 1991;18:93-100

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The relation between the arterioiar diameters and hypertensive glomeruioscierosis was studied by using microvascular casts and histological evaluation. Spontaneously hypertensive rats 4 weeks of age were divided into three groups: nontreated, captopril (40 mg/kg/day)-treated, and trichlormethlazide (1 mg/kg/day) with hydralazine (20 mg/kg/day)-treated. Wistar-Kyoto rats served as controls. At 6 weeks old, the captopril-treated rats showed a lower blood pressure and a larger afferent arterioiar diameter compared with the control rats. At 20 weeks old, the nontreated group exhibited hypertension and a lower arterioiar diameter ratio (afferent to efferent, 0.89 versus 1.22 in control group) because of afferent constriction and efferent dilatation, seen equally in the outer and inner cortexes. Glomeruioscierosis was accentuated only in the inner cortex of the nontreated group (score, 63 versus 29 in control group). In the two treated rat groups, the blood pressure was reduced and arterioiar diameter ratios were similar to those in the control group (1.18 and 1.26). The sclerosis score in the trichlormethiazide with hydralazine-treated rats (score, 26) was lower than in the nontreated rats but not the captopril-treated rats (score, 36). These results indicated that 1) in the hypertensive rats, despite a reduced diameter ratio, glomeruioscierosis was more severe in the inner cortex; 2) two therapies reduced blood pressure and reversed the arterioiar changes, but a decrease in glomeruioscierosis was seen only in the trichlormethiazide with hydralazine-treated rats; and 3) for development of glomeruioscierosis, factors other than hemodynamics may be important in addition to intraglomerular pressure.

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We have reported that the basal and stimulated cytosolic free calcium concentrations ([Ca2+]i) are elevated in platelets isolated from 12-14-week-old spontaneously hypertensive rats (SHR) as compared with nonnotensive Wistar-Kyoto (WKY) rats. To determine whether altered cell calcium metabolism precedes the development of overt hypertension, we measured [Ca2+]t under resting and stimulated conditions in blood platelets and thymic lymphocytes isolated from 4-week-old prehypertensive SHR and WKY rats. Blood pressure was similar in both groups (SHR 95 ±8 versus WKY rats 92±7 mm Hg). Basal [CaJ+], in platelets was higher in SHR than WKY rats (63.4±3.9 versus 54.8±3.1 nM, p<0.003). Also the [Ca2+], response to thrombin was greater in SHR than WKY rats in both the presence and absence of extracellular calcium. For lymphocytes, although no difference was detected in basal [Ca2+]b the concanavalin A-induced peak [Ca2+], was higher for SHR than WKY rats in both calcium-containing and calcium-free media. These results suggest that agonist-stimulated calcium influx and calcium discharge from intracellular stores are enhanced in both platelets and lymphocytes of 4-week-old SHR. We conclude that abnormalities in calcium metabolism in two different cell types precede the development of overt hypertension in the SHR.

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This study examined the effect of moderate ethanol intake on systolic blood pressure, platelet cytosolic free calcium, aortic calcium, and rubidium- 86 uptake in Wistar-Kyoto rats. Twelve Wistar-Kyoto rats, aged 6 weeks, were given 5% ethanol in drinking water the first week followed by 10% ethanol in drinking water for the next 6 weeks. Twelve control animals were given regular tap water. Systolic blood pressure in the ethanol-treated rats was significantly higher (p<0.05) than that in controls after 1 week and remained higher throughout the study. At 13 weeks of age, platelet cytosolic free calcium and calcium uptake by aortas were significantly higher (p< 0.001) in ethanol-treated animals as compared with those in controls. Ethanol intake did not affect aortic ouabain-sensitive wRb uptake. The in vitro effect of ethanol on calcium-45 and MRb uptake was also investigated in aortas of untreated Wistar-Kyoto rats at 13 weeks of age. In vitro ethanol (2.5-20 mmol/1) did not significantly affect 4SCa and MRb uptake in rat aortas. The increases in systolic blood pressure, platelet cytosolic free calcium, and vascular calcium uptake suggest that increases in cytosolic free calcium and calcium uptake mechanisms are associated with ethanol-induced hypertension.

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0194-911X    

出版商:OVID    

年代:1991

数据来源: OVID