ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: To determine the effect of angiotensin converting enzyme inhibition (CEI) upon renal function and the incidence of glomerulosclerosis in spontaneously hypertensive Fawn Hooded rats (FHR)Design: Male FHR were treated with captopril from the age of 5 months when mild hypertension, proteinuria and glomerulosclerosis are present, and sacrificed at 12 months of age. Renal function was determined in separate groups of FHR at 6 months of ageMethods: Proteinuria, body weight and systolic blood pressure were determined at regular intervals. Blood pressure was measured by the tail-cuff method. Kidneys were prepared for histological examination by standard methods. Renal function was determined by inulin clearance and urinary kallikrein by an amydolitic assayResults: In untreated FHR blood pressure, proteinuria and glomerulosclerosis increased with time. Captopril normalized blood pressure and stabilized proteinuria at pretreatment levels. At the end of the study, the incidence of glomerulosclerosis was significantly lower and comparable with the incidence at 5 months. Glomerular volume did not show a correlation with the incidence of glomerulosclerosis. Hemodynamic studies showed a significant increase of glomerular filtration rate in captopril-treated rats. No statistically significant effect was seen on renal plasma flow or filtration fraction. Urinary excretion of kallikrein was increased in captopril-treated ratsConclusions: CEI is effective in protecting the kidney from structural damage in hypertensive FHR even when treatment is started under conditions of established glomerular injury. The protection given by captopril is probably related to intrarenal effects

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: This study aimed to examine the role of the renin–angiotensin system in the regulation of kidney haemodynamic and excretory function when angiotensin II levels were modestly and markedly raisedDesign: Three groups of male Sprague—Dawley rats were used: control rats fed a sodium-replete diet; rats fed a sodium-deficient diet for 2 weeks; and two-kidney, one clip (2K1C) Goldblatt hypertensive rats, 4—5 weeks postclippingMethods: The rats were acutely anaesthetized with sodium pentobarbitone and prepared for renal function measurements. The converting enzyme inhibitor, cilazapril, was then infused at increasing dose levels to progressively block the renin–angiotensin systemResults: Cilazapril did not affect blood pressure in sodium-replete animals; it raised RBF and increased water and sodium excretion. In dietary sodium-depleted rats, cilazapril decreased blood pressure and increased RBF, water and sodium excretion at the lower doses of the drug; however, at vasodepressor doses, water and sodium excretion fell towards baseline values. In 2K1C Goldblatt hypertensive rats, cilazapril maximally decreased blood pressure whilst the non-clipped kidney blood flow, filtration rate and fluid excretion rates were similar to dietary sodium-depleted rats; in contrast, the clipped kidney filtration rate was well maintained and fluid excretion was raised in a dose-related fashion.Conclusion: These results show that during gradual cilazapril administration, renal function is well preserved in 2K1C Coldblatt hypertensive rats when pressure is progressively reduced

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: Left ventricular function (LVF) after reversal of left ventricular hypertrophy (LVH) with antihypertensive therapy is still controversial. The present study was undertaken in spontaneously hypertensive rats (SHR) to determine whether LVF of the regressed heart with lisinopril is normally maintainedDesign: We compared cardiac function of SHR after reversal of LVH induced by lisinopril with that observed in control SHR and also with effects after a 4-week washout periodMethods: Administration of lisinopril began at 15 weeks of age and continued for 20 weeks. Cardiac index, renal blood flow, leg muscle blood flow, plasma renin activity, atrial natriuretic peptide level, and norepinephrine concentration were determinedResults: Lisinopril decreased body weight, blood pressure and left ventricular weight and increased leg muscle blood flow; cardiac index and renal blood flow were unaltered. Although norepinephrine concentration was unchanged, plasma renin activity increased and atrial natriuretic peptide decreased in treated SHR. Peak left ventricular pumping ability during volume loading was comparable in the two groups. After a 4-week washout period, left ventricular mass and blood pressure increased but remained lower than controls; cardiac index at rest and during volume loading was similar in the two groupsConclusions: These data indicate that LVF of the regressed heart induced by lisinopril was well preserved at rest, during volume loading and also after spontaneous recurrence of hypertension in SHR

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: In experimental models of hypertension in the rat, resistance arteries present a blunted response to endothelin, a potent vasoconstrictor peptide. The primary objective of this study was to investigate whether, as in hypertensive rat blood vessels, the response of human resistance arteries to endothelin was altered in essential hypertensive patients, in order to further understand the possible physiopathological involvement of this peptide in human hypertensionDesign: Normotensive male subjects and sex- and age-matched mild essential hypertensive patients who had not received antihypertensive drugs for more than 6 months were investigatedMethods: Small arteries were dissected from gluteal subcutaneous biopsies and mounted on a wire-myograph. Blood vessels were measured and dose-response curves to different agents testedResults: The external diameter of blood vessels of the hypertensive patients tended to be smaller and the width of their media tended to be thicker, but the cross-sectional area of the wall was similar in both groups. Lumen diameters were significantly smaller in hypertensives and the media: lumen ratio was significantly increased in hypertensive patients. Active tension responses and sensitivity to norepinephrine, arginine vasopressin and angiotensin II were similar in both groups, but calculated active pressure responses were enhanced in hypertensives due to the smaller blood vessel lumen. Tension responses to endothelin-1 at increasing concentrations of 0.1 to 100nmol/l were lower in hypertensive patients, but the calculated transmural active pressure developed was not significantly different at or above 10nmol/lConclusion: These results suggest that gluteal subcutaneous small resistance arteries of male essential hypertensive patients exhibit a decrement in responsiveness to endothelin-1. The altered design of the hypertensive blood vessels enhanced calculated pressure responses, which may contribute to the maintenance of elevated blood pressure

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: Renin secretion in response to long-term exposure to isoprenaline, dibutyryl cyclic adenosine monophosphate (dbcAMP), forskolin and atrial natriuretic peptide (ANP) was measured in cultured human nephroblastoma cellsMethods: Human nephroblastoma cells in culture were treated long-term (1-12 days) with isoprenaline, dbcAMP or forskolin, alone or in combination with ANP; renin release and cell growth were studiedResults: The increase in renin output caused by isoprenaline and dbcAMP could be accounted for by stimulation of cell growth. The effect of isoprenaline was blocked by propanolol. Forskolin stimulated renin secretion per cell. ANP increased extracellular cyclic guanosine monophosphate and suppressed basal renin output. Suppression of basal renin output was due to a reduced secretion rate per cell, without a change in cell growth. ANP suppressed isoprenaline-induced and dbcAMP-induced renin output by blocking increased cell growth, and forskolin-induced renin output by blocking renin secretionConclusions: These results suggest that (3-receptor agonists and ANP interact within the kidney to control renin secretion, by helping to determine the number of renin-secreting cells

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective:The main aim of this study was to examine whether atrial natriuretic peptide (ANP) alters capillary filtration and venous distensibilityDesign:The study was designed to examine the local effects of i.a. infusion of ANP upon capillary filtration and venous distensibility in human forearms of eight healthy volunteersMethods:Using a water plethysmograph, we measured venous distensibility and capillary filtration from changes in forearm volume when transmural venous pressure was increased in a stepwise manner and held constant during i.a. infusion of saline, ANP and sodium nitroprusside (SNP). The doses of ANP and SNP were chosen to double baseline forearm blood flow obtained during saline infusionResults:ANP and SNP infusion both increased venous distensibility to the same extent compared with saline infusion. Capillary filtration was greater during ANP than during saline or SNP infusion. Small vein pressure was comparable during infusion of the two drugsConclusion:Our results suggest that ANP increases venous distensibility and capillary filtration in human forearms

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objective: To test the hypothesis of reduced venous compliance and increased cardiovascular responses to volume expansion and α -agonist stimulationMethod: Non-hypertensive healthy young men with positive (PFH) and negative family histories of hypertension were investigated regarding peripheral haemodynamics and changes in central venous pressure (CVP) and arterial blood pressure in response to graded doses of phenylephrine and acute i.v. fluid volume loading (1000 saline solution in 10 min). The control group was divided into one group matched for body mass index to PFH subjects (NFHO) and one lean control group (NFHN)Results: Supine blood pressure was higher in PFH and NFHO subjects compared with NFHN subjects, whilst CVP was similar in the three groups at baseline. No significant differences in calf or forearm haemodynamics or blood volume were observed between the three groups. Cardiovascular responses to bolus doses of phenylephrine did not differ between the three groups. Saline infusion significantly increased CVP and systolic blood pressure, and effective vascular compliance (change in blood volume: CVP ratio) was reduced in PFH subjectsConclusion: PFH subjects have decreased effective vascular compliance and altered arterial blood pressure responses to acute increases in vascular fluid volume. This may result from multiple factors such as increased venous vascular tone, structural reduction of venous distensibility and/or an altered neurohormonal response to increased CVP

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Objectives:To examine the relationship of blood pressure with haematocrit, plasma viscosity, whole blood viscosity and plasma fibrinogen.Design:A random population sample of 1264 men and women aged 25—64 years from the west of Scotland, UK.Results:Strong correlations between age, body mass index and blood pressure were noted: these were higher for women than men. Blood viscosity, haematocrit and plasma viscosity correlated with blood pressure independently of age, body mass index and smoking status. No evidence was found for an effect of erythrocyte rigidity upon blood pressure; plasma fibrinogen showed an inverse correlation with blood pressure and the rheological variables on multivariate analysis.Conclusions:Our findings support the role of blood viscosity in determining blood pressure as suggested by other, smaller studies. The magnitude of the effect upon blood pressure levels across the normal range of blood viscosity was of clinical importance. Further studies of factors that influence blood and plasma viscosity may help in the understanding of the aetiology of essential hypertension and its management.

ISSN:0263-6352    

出版商:OVID    

年代:1992

数据来源: OVID