PubMed Health⌕ Search

Biomedical subjects

J J McMurray

Publications and source records attributed to J J McMurray.

At least 19 recordsLinked to original sources

Age, sex, and social trends in out-of-hospital cardiac deaths in Scotland 1986-95: a retrospective cohort study.

BACKGROUND: Most deaths from coronary heart disease occur out of hospital. Hospital patients face social, age, and sex inequalities. Our aim was to examine inequalities and trends in out-of-hospital cardiac deaths. METHODS: We used the Scottish record linked database to identify all deaths from acute myocardial infarction that occurred in Scotland (population 5.1 million), in 1986-95. We have compared population-based death rates for men and women across age and social groups. FINDINGS: Between 1986 and 1995, 83365 people died from acute myocardial infarction, out of hospital and without previous hospital admission (44655 men, 38710 women); and 117749 were admitted with a first acute myocardial infarction, of whom 37020 died within 1 year. Thus, out-of-hospital deaths accounted for 69.2% (95% CI 69.0-69.5) of all 120385 deaths. Out-of-hospital deaths, measured as a proportion of all acute myocardial infarction events (deaths plus first hospital admissions), increased with age, from 20.1% (19.2-21.0) in people younger than 55 years, to 62.1% (61.3-62.9) in those older than 85 years. Population-based out-of-hospital mortality rates fell by a third in men and by a quarter in women. Mean yearly falls were larger in people aged 55-64 years (5.6% per year in men, 3.7% in women), than in those older than 85 years (2.5% in men and women). Mortality rates were substantially higher in deprived socioeconomic groups than in affluent groups, especially in people younger than 65 years. INTERPRETATION: These inequalities in age, sex, and socioeconomic class should be actively addressed by prevention strategies for coronary heart disease.

Age Distribution↗

Vasoconstrictor effect of the angiotensin-converting enzyme-resistant, chymase-specific substrate [Pro(11)(D)-Ala(12)] angiotensin I in human dorsal hand veins: in vivo demonstration of non-ace production of angiotensin II in humans.

BACKGROUND: [Pro(11)(D)-Ala(12)] angiotensin I is an ACE-resistant substrate specific for chymase. We used this peptide to determine whether a functionally significant non-ACE angiotensin (Ang) II-generating pathway exists in human dorsal hand veins. METHODS AND RESULTS: Using a modified Aellig technique, we studied the response to Ang I and [Pro(11)(D)-Ala(12)] Ang I in dorsal hand veins in vivo in patients with coronary heart disease. We measured the venoconstrictor effect of each peptide given before and after a 6.25-mg oral dose of the ACE inhibitor captopril or matching placebo. Placebo or captopril was given in a double-blind, randomized fashion. Ang I induced a mean+/-SEM venoconstrictor response of 45+/-11%, 40+/-10%, 55+/-8%, and 4+/-4% before placebo, after placebo, before captopril, and after captopril, respectively. Hence, the response to Ang I was reproducible and was reduced significantly only after treatment with captopril (P=0.002). [Pro(11)(D)-Ala(12)] Ang I induced a mean venoconstrictor response of 42+/-9%, 49+/-9%, 48+/-10%, and 54+/-11% before placebo, after placebo, before captopril, and after captopril, respectively. Hence, captopril had no significant effect on the response to [Pro(11)(D)-Ala(12)] Ang I. CONCLUSIONS: We have demonstrated that [Pro(11)(D)-Ala(12)] Ang I is able to induce venoconstriction in humans in vivo. With this specific pharmacological probe, we have shown that a non-ACE pathway capable of generating Ang II exists in human veins in vivo and is potentially functionally important. This pathway is likely to involve the enzyme chymase.

Administration, Oral↗

Randomised controlled trial of specialist nurse intervention in heart failure.

OBJECTIVES: To determine whether specialist nurse intervention improves outcome in patients with chronic heart failure. DESIGN: Randomised controlled trial. SETTING: Acute medical admissions unit in a teaching hospital. PARTICIPANTS: 165 patients admitted with heart failure due to left ventricular systolic dysfunction. The intervention started before discharge and continued thereafter with home visits for up to 1 year. MAIN OUTCOME MEASURES: Time to first event analysis of death from all causes or readmission to hospital with worsening heart failure. RESULTS: 31 patients (37%) in the intervention group died or were readmitted with heart failure compared with 45 (53%) in the usual care group (hazard ratio=0.61, 95% confidence interval 0.33 to 0.96). Compared with usual care, patients in the intervention group had fewer readmissions for any reason (86 v 114, P=0.018), fewer admissions for heart failure (19 v 45, P<0.001) and spent fewer days in hospital for heart failure (mean 3.43 v 7.46 days, P=0.0051). CONCLUSIONS: Specially trained nurses can improve the outcome of patients admitted to hospital with heart failure.

Aged↗

Endothelium-derived hyperpolarizing factor : identification and mechanisms of action in human subcutaneous resistance arteries.

BACKGROUND: Both a vascular endothelial cytochrome P450 (CYP450) product of arachidonic acid metabolism and the potassium ion (K(+)) have been identified as endothelium-derived hyperpolarizing factors (EDHFs) in animal vascular tissues. We studied the relative importance of EDHF, nitric oxide (NO), and prostacyclin (PGI(2)) as vasodilators in human subcutaneous arteries. We also examined the mechanisms underlying the vasodilator action of EDHF to elucidate its identity. METHODS AND RESULTS: Subcutaneous resistance arteries were obtained from 41 healthy volunteers. The contribution of EDHF to the vasodilation induced by acetylcholine was assessed by inhibiting production of NO, PGI(2), and membrane hyperpolarization. The mechanisms underlying the relaxation evoked by K(+) and EDHF were elucidated. EDHF was found to account for approximately 80% of acetylcholine-mediated vasorelaxation. Its action was insensitive to the combination of barium and ouabain, whereas barium and ouabain reversed K(+)-mediated vasorelaxation. EDHF-mediated vasorelaxation, however, was sensitive to the phospholipase A(2) inhibitor oleyloxyethyl phosphorylcholine and the CYP450 inhibitor ketoconazole. CONCLUSIONS: EDHF is the major contributor to endothelium-dependent vasorelaxation in human subcutaneous resistance arteries. A product of phospholipase A(2)/CYP450-dependent metabolism of arachidonic acid and not K(+) is the likely identity of EDHF in human subcutaneous resistance arteries.

Acetylcholine↗

Angiotensin converting enzyme (ACE) and non-ACE dependent angiotensin II generation in resistance arteries from patients with heart failure and coronary heart disease.

OBJECTIVES: We sought to demonstrate non-angiotensin converting enzyme (ACE) dependent angiotensin II (AII) generating pathways in resistance arteries from patients with chronic heart failure (CHF). BACKGROUND: Non-ACE dependent AII generation occurs in resistance arteries from normal volunteers. Inhibition of non-ACE dependent AII generation may have therapeutic potential in CHF. METHODS: Resistance arteries were dissected from gluteal biopsies from patients with coronary heart disease (CHD) and preserved left ventricular function and from patients with CHF. Using wire myography, concentration response curves to angiotensin I (AI) and AII were constructed in the presence of 1) vehicle, 2) chymostatin [an inhibitor of chymase], 3) enalaprilat, and 4) the combination of chymostatin and enalaprilat. RESULTS: In resistance arteries from patients with CHD, the vasoconstrictor response to AI was not inhibited by either inhibitor alone (chymostatin [p > or = 0.05] or enalaprilat [p > or = 0.05]) but was significantly inhibited by the combination (p < 0.001). In arteries from patients with CHF, AI responses were inhibited by enalaprilat (p < 0.05) but not by chymostatin alone (p > 0.05). The combination ofchymostatin and enalaprilat markedly inhibited the response to AI (p < 0.001) to a greater degree than enalaprilat alone (p < or = 0.01). CONCLUSIONS: Non-ACE dependent AII generating pathways exist in resistance arteries from patients with both CHF and CHD. In resistance arteries from patients with CHD, inhibition of either the ACE or chymase pathway alone has no effect on AII generation, and both pathways must be blocked before the vasoconstrictor action of AI is inhibited. In CHF, blockade of ACE results in marked inhibition of responses to AI, but this is enhanced by coinhibition of chymase. These studies suggest that full suppression of the renin-angiotensin system cannot be achieved by ACE inhibition alone and provide a rationale for developing future therapeutic strategies.

Acetylcholine↗

Are angiotensin II receptor blockers more efficacious than placebo in heart failure? Implications of ELITE-2. Evaluation of Losartan In The Elderly.

In the light of the recent randomized controlled trials in chronic heart failure, it is now commonly assumed that treatment with an angiotensin-receptor blocker (ARB) is equivalent to treatment with an angiotensin-converting enzyme (ACE) inhibitor. We performed an imputed placebo analysis using previous placebo-ACE inhibitor trials and the current ACE inhibitor-ARB comparison studies, which shows that ARBs may not even be superior to placebos, let alone an ACE inhibitor.

Aged↗

Signalling mechanisms underlying the myogenic response in human subcutaneous resistance arteries.

OBJECTIVE: In this study we have examined for the first time the signal transduction mechanisms involved in the generation of pressure-dependent myogenic tone in human small resistance arteries from the subcutaneous vascular bed. METHODS: Myogenic responses and the subcellular mechanisms involved in the generation of this response were studied on a pressure myograph. RESULTS AND CONCLUSION: Human subcutaneous resistance arteries constricted 14.1+/-1.1% in response to an increases in intraluminal pressure from 40 to 80 mmHg and a further 3.5+/-1.7% in response to the 80-120-mmHg pressure step. Ca(2+) depletion or nifedipine abolished this response, whereas BAY K 8644 increased this response to 20.6+/-2.1% (P<0.05, response vs. control). The phospholipase C inhibitor U-73122 reduced the myogenic response to 2.5+/-1.0% at 80 mmHg (P<0.01, response vs. control) and abolished it at 120 mmHg. Diacylglycerol lipase inhibition with RHC-80267 abolished all myogenic responses to pressure. The protein kinase C (PKC) activator phorbol 12,13-dibutyrate increased the maximal myogenic response to 20.9+/-1.8% (P<0.05, response vs. control), whereas the PKC inhibitor calphostin C abolished myogenic responses. These data show that the generation of pressure-dependent myogenic tone in human subcutaneous arteries is dependent on Ca(2+) influx via voltage operated Ca(2+) channels (VOCCs) and a concomitant requirement for the activation of phospholipase C (PLC), diacylglycerol, and PKC.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

Electrical cardioversion for atrial fibrillation: outcomes in "real-life" clinical practice.

BACKGROUND: There is currently considerable debate with regard to the optimal management of atrial fibrillation/flutter (AF), including the long-term success of electrical cardioversion and the duration of anti-coagulation thereafter. The aim of this study was to investigate the current management and outcomes of electrical cardioversion in unselected patients in ordinary clinical practice. METHODS: A prospective, observational study of 111 consecutive patients with AF who had been referred for electrical cardioversion was undertaken in a large teaching hospital. After cardioversion, patients were followed-up for 12 months or until death if this occurred earlier. RESULTS: Sinus rhythm was restored immediately in 96 of 111 (86%) patients. Only 54 of 88 (61%) patients in sinus rhythm at discharge remained in this rhythm at 1 month. Of these 54, a further 21 (39%) had relapsed into AF by 12 months. Independent predictors of sinus rhythm at discharge were younger age (for a difference of 5 years, odds ratio=1.54; 95% confidence interval 1.04 to 1.16; P=0.002) and absence of hypertension (1.73, 1.22-1.91; P=0.015). The presence of sinus rhythm at discharge (6.4, 1.6-25.3; P=0.007) was an independent predictor of sinus rhythm at 1 month, whereas older age was a negative predictor (0.96, 0.92-1.0; P=0.05). Health-related quality of life improved at 1 and 12 months in those patients who remained in sinus rhythm compared to those who remained in AF. CONCLUSIONS: Though electrical cardioversion for AF has a high initial success rate only a minority of patients remained in sinus rhythm 1 year. The common practice of discontinuing anticoagulant treatment in patients in sinus rhythm at 1 month may be unsafe. Long-term maintenance of sinus rhythm is, however, associated with better health-related quality of life.

Aged↗

Attenuation of endothelin-1 induced vasoconstriction by 17beta estradiol is not sustained during long-term therapy in postmenopausal women with coronary heart disease.

OBJECTIVES: The goal of this study was to determine the long-term effects of estrogen replacement therapy on the response to endothelin-1 (ET-1) in postmenopausal women with coronary heart disease. BACKGROUND: It is thought that the vasoconstrictor ET-1 is involved in the development and progression of atherosclerosis. Estrogen replacement may slow the development of atherosclerosis in postmenopausal women. METHODS: Nineteen of 20 postmenopausal women randomized to either three months of 2 mg oral estradiol or placebo completed the double-blind placebo-controlled protocol. Change in forearm blood flow (FBF) in response to a 60 min brachial arterial infusion of ET-1 (5 pmol/min) was measured before randomization, after one month of randomized therapy and after three months of therapy using venous occlusion plethysmography. RESULTS: Estrogen treatment had no effect on baseline FBF. Systolic and diastolic blood pressure and heart rate did not change in response to estrogen therapy or ET-1. Before randomization, in response to ET-1, FBF was reduced by -21.9% (mean response over 60 min) in the placebo group and -19.0% in the estradiol group (p = 0.67). After one month of therapy, the response was attenuated in the estrogen group, -10.0%, compared with the placebo group, -23.6 (difference in means 13.6%, 95% confidence interval [0.7%, 26.6%], p = 0.041). After three months of therapy, there was no difference in response between the placebo group, -27.0%, and estrogen group, -30.2% (p = 0.65). CONCLUSIONS: In postmenopausal women with coronary heart disease, estrogen therapy inhibits the vasoconstrictor response to ET-1 after one month of therapy. This effect is lost after three months of therapy, suggesting that tachyphylaxis to one potentially beneficial action of estradiol develops during chronic treatment.

Aged↗

Aspirin inhibits the acute venodilator response to furosemide in patients with chronic heart failure.

OBJECTIVES: We sought to determine the effect of aspirin on the venodilator effect of furosemide in patients with chronic heart failure (CHF) BACKGROUND: Furosemide has an acute venodilator effect preceding its diuretic action, which is blocked by nonsteroidal anti-inflammatory, drugs. The ability of therapeutic doses of aspirin to block this effect of furosemide in patients with CHF has not been studied. For comparison, the venodilator response to nitroglycerin (NTG) was also studied. METHODS: Eleven patients with CHF were randomized to receive placebo, aspirin at 75 mg/day or aspirin at 300 mg/day for 14 days in a double-blind, crossover study. The effect of these pretreatments on the change in forearm venous capacitance (FVC) after 20 mg of intravenous furosemide was measured over 20 min by using venous occlusion plethysmography. In a second study, the effect of 400 microg of sublingual NTG on FVC was documented in 11 similar patients (nine participated in the first study). RESULTS: Mean arterial pressure, heart rate and forearm blood flow did not change in response to furosemide. After placebo pretreatment, furosemide caused an increase in FVC of 2.2% (95% confidence interval [CI] -0.9% to 5.2%; mean response over 20 min). By comparison, FVC fell by -1.1% (95% CI -4.2% to 1.9%) after pretreatment with aspirin at 75 mg/day, and by -3.7% (95% CI -6.8% to -0.7%) after aspirin at 300 mg/day (p = 0.020). In the second study, NTG increased FVC by 2.1% (95% CI -1.6% to 5.8%) (p = 0.95 vs. furosemide). CONCLUSIONS: In patients with CHF, venodilation occurs within minutes of the administration of intravenous dose of furosemide. Our observation that aspirin inhibits this effect further questions the use of aspirin in patients with CHF.

Aged↗

Gender and survival: a population-based study of 201,114 men and women following a first acute myocardial infarction.

OBJECTIVES: We tested the hypotheses that the effect of gender on short-term case fatality following a first admission for acute myocardial infarction (AMI) varies with age, and that this effect is offset by differences in the proportion of men and women who survive to reach hospital. BACKGROUND: Evidence is conflicting regarding the effect of gender on prognosis after AMI. METHODS: All 201,114 first AMIs between 1986 and 1995 were studied. Both 30-day and 1-year case fatality were analyzed for the 117,749 patients hospitalized and for all first AMIs, including deaths before hospitalization. The effect of gender and its interaction with age on survival was examined using multivariate modeling. RESULTS: Gender-based differences in survival varied according to age in hospitalized patients, with younger women having higher 30-day case fatality than men (e.g., <55 years, women 6.5% vs. 4.8% men, p < 0.0001). When deaths from first AMI before hospitalization were included in 30-day case fatality, women were less likely to die (adjusted odds ratio 0.9, confidence interval 0.89 to 0.93). Gender was not an independent predictor of one-year survival (p = 0.16). CONCLUSIONS: Female gender increases the probability of surviving to reach hospital, and this outweighs the excess risk of death occurring in younger women following hospitalization. Overall, men have a higher 30-day case fatality than women. Women do not fare worse than men after AMI when age and other factors are taken into account. However, men are more likely to die before hospitalization.

Age Factors↗

Altered diaphragm position and function in patients with chronic heart failure.

BACKGROUND: Breathlessness is a common symptom experienced by patients with chronic heart failure (CHF) but its etiology remains controversial. Various molecular and histological adaptations have been reported for the diaphragm in CHF but their functional consequences are poorly described. AIMS: This study aims to determine the position and function of the diaphragm in CHF patients. METHODS: The diaphragm position was measured, relative to the renal pelvis, by ultrasound in 20 CHF patients and ninety controls matched for age and body mass. The extent and velocity of diaphragm movement was also measured during quiet breathing and sniffing. RESULTS: At the end of expiration, the diaphragm was significantly nearer to the renal pelvis in CHF patients (89.3+/-16.8 vs. 96.3+/-19.2 mm, P<0.05) and also moved further during quiet breathing (18.2+/-4.4 vs. 12.7+/-4.6 mm, P<0.001) and sniffing (23.9+/-7.4 vs. 18.2+/-5.7 mm, P<0.005). Velocity of diaphragm movement was also increased in CHF patients during quiet breathing (26.5+/-8.2 vs. 15.9+/-6.1 mm s(-1), P<0.001). CONCLUSIONS: These data demonstrate that the position and function of the diaphragm is altered in CHF.

Aged↗

More 'malignant' than cancer? Five-year survival following a first admission for heart failure.

BACKGROUND: The prognostic impact of heart failure relative to that of 'high-profile' disease states such as cancer, within the whole population, is unknown. METHODS: All patients with a first admission to any Scottish hospital in 1991 for heart failure, myocardial infarction or the four most common types of cancer specific to men and women were identified. Five-year survival rates and associated loss of expected life-years were then compared. RESULTS: In 1991, 16224 men had an initial hospitalisation for heart failure (n=3241), myocardial infarction (n=6932) or cancer of the lung, large bowel, prostate or bladder (n=6051). Similarly, 14842 women were admitted for heart failure (n=3606), myocardial infarction (n=4916), or cancer of the breast, lung, large bowel or ovary (n=6320). With the exception of lung cancer, heart failure was associated with the poorest 5-year survival rate (approximately 25% for both sexes). On an adjusted basis, heart failure was associated with worse long-term survival than bowel cancer in men (adjusted odds ratio, 0.89; 95% CI, 0.82-0.97; P<0.01) and breast cancer in women (odds ratio, 0.59; 95% CI, 0.55-0.64; P<0.001). The overall population rate of expected life-years lost due to heart failure in men was 6.7 years/1000 and for women 5.1 years/1000. CONCLUSION: With the notable exception of lung cancer, heart failure is as 'malignant' as many common types of cancer and is associated with a comparable number of expected life-years lost.

Age Factors↗

Poles apart, but are they the same? A comparative study of Australian and Scottish patients with chronic heart failure.

This paper reports on an international comparison of the characteristics, treatment and health outcomes of chronic heart failure (CHF) patients discharged from acute hospital care in Australia and Scotland. The baseline characteristics and treatment of 200 CHF patients recruited to a randomised study of a non-pharmacological intervention in Australia and 157 CHF patients concurrently recruited to a similar study in Scotland were compared. Subsequent health outcomes (including survival and readmission) within 3 months of discharge in those patients who received usual post-discharge care in Australia (n=100) and Scotland (n=75) were also compared. Individuals in both countries were predominantly old and frail with significant comorbidity likely to complicate treatment. Similar proportions of Australian and Scottish patients were prescribed either a 'high' (20 vs. 18%) or medium (64 vs. 66%) dose of an angiotensin-converting enzyme inhibitor. Proportionately more Australian patients were prescribed a long-acting nitrate, digoxin and/or a beta-blocker. At 3 months post-discharge, 57 of the 100 (57%: 95% CI 47--67%) Australian and 37 of the 75 (49%: 95% CI 38--61%) Scottish patients assigned to 'usual care' remained event-free (NS). Similarly, 15 vs. 12% required > or =2 unplanned readmission (NS) and 16 vs. 19% of Australian and Scottish patients, respectively, died (NS). Australian and Scottish patients accumulated a median of 0.6 vs. 0.9 days, respectively, of hospitalisation/patient/month (NS). On multivariate analysis (including country of origin), unplanned readmission or death was independently correlated with severe renal impairment (adjusted odds ratio 4.4, P<0.05), a previous hospitalisation for CHF (2.3, P<0.05), longer index hospitalisation (2.7 for >10 days, P<0.05) and greater comorbidity (1.3 for each incremental unit of the Charlson Index, P=0.05). Health outcomes among predominantly old and frail CHF patients appear to be independent of the health-care system in which the patient is managed and more likely to be dependent on the syndrome itself.

Aged↗

Economics of chronic heart failure.

Chronic heart failure (CHF) is now recognized as a major and escalating public health problem. The costs of this syndrome, both in economic and personal terms, are considerable. The prevalence of CHF is 1-2% and appears to be increasing, in part because of ageing of the population. Economic analyses of CHF should include both direct and indirect costs of care. Healthcare expenditure on CHF in developed countries consumes 1-2% of the total health care budget. The cost of hospitalization represents the greatest proportion of total expenditure. Optimization of drug therapy represents the most effective way of reducing costs. Recent economic analyses in the Netherlands and Sweden suggest the costs of care are rising.

Chronic Disease↗

Clinical experience with endothelin receptor antagonists in chronic heart failure.

Both ET(A) selective and dual, ET(A/B), receptor antagonists have favourable short- and longer-term haemodynamic actions in patients with acute and chronic heart failure. Their effect on neurohumoral measures is not yet fully determined. Two moderately large, medium-duration studies have examined the effect of dual ET(A/B) receptor antagonists on clinical status, reaching conflicting conclusions. One large scale, long-term, morbidity mortality evaluation is underway with bosentan.

Chronic Disease↗

Effects of adrenomedullin on angiotensin II stimulated atrial natriuretic peptide and arginine vasopressin secretion in healthy humans.

AIMS: Adrenomedullin is a newly described peptide that has widespread tissue distribution. Its presence in cardiovascular (including vascular endothelial cells, smooth muscle cells, and cardiac atria and ventricles) and renal tissues, together with its vasodilatory and natriuretic properties, suggest a role in blood pressure regulation and fluid and electrolyte balance. METHODS: Nine normal volunteers were studied to determine whether or not adrenomedullin influenced plasma atrial natriuretic peptide and arginine vasopressin concentrations during systemic angiotensin II infusion. RESULTS: A significant (P = 0.02) augmentation of atrial natriuretic peptide concentrations, but no suppression of arginine vasopressin concentrations, was found with coinfusion of adrenomedullin and angiotensin II when compared with vehicle and angiotensin II. CONCLUSIONS: Despite its vasodilator and natriuretic action, adrenomedullin significantly augmented angiotensin II-stimulated plasma atrial natriuretic peptide concentrations in healthy humans. This provides further evidence of a synergistic interaction between adrenomedullin and atrial natriuretic peptide and suggests that adrenomedullin may have a role in fluid and electrolyte balance and blood pressure regulation.

Adrenomedullin↗

Impaired endothelial function in isolated human uremic resistance arteries.

BACKGROUND: Patients with chronic renal failure (CRF) face a markedly increased risk of cardiovascular death. CRF is frequently complicated by hypertension and changes in both the heart (left ventricular hypertrophy) and the vasculature (endothelial dysfunction and accelerated atherosclerosis). The mechanisms underlying changes in vascular function and specifically endothelial dysfunction are unclear. This present study therefore examined subcutaneous resistance artery function in vitro, comparing adult uremic patients and controls using wire myography. METHODS: Subcutaneous fat biopsies were obtained from 12 patients with CRF (median serum creatinine 735 micromol/L) at the time of renal transplantation or peritoneal dialysis catheter insertion, and from eight controls without renal disease at the time of abdominal surgery. Resistance arteries were mounted on a wire myograph. Their contractile ability was tested with high potassium depolarization, and endothelial integrity was tested by relaxation to acetylcholine. Cumulative concentration-response curves were then constructed for norepinephrine, endothelin-1, acetylcholine, and sodium nitroprusside (SNP). RESULTS: Following preconstriction with norepinephrine, vessels from uremic patients vasodilated less well to acetylcholine compared with vessels from controls [maximum % relaxation 77% (range 41, 97) vs. 98% (78, 100), P < 0.001]. The vasodilation to SNP was similar [95% (63, 100) vs. 94% (71, 100), P = 0.751]. There was a trend toward increased maximum pressure (kPa) achieved with both norepinephrine and endothelin-1 in vessels from uremic patients, and the contractions to both of these agents were more prolonged in the uremic vessels. CONCLUSIONS: The pattern of normal vasodilation to SNP but reduced vasodilation to acetylcholine is consistent with endothelial dysfunction due to impaired nitric oxide (NO) production in uremic vessels. Similar results have been demonstrated in vivo in uremia, one suggested mechanism being accumulation of endogenous inhibitors of NO synthase such as asymmetric dimethylarginine (ADMA). This in vitro study suggests that a short-lived circulating factor is not entirely responsible and that there may be an inherent abnormality in endothelial function in uremia, although the exact pathophysiology remains unclear. Endothelial dysfunction may predispose the patient to accelerated atherosclerosis and may be involved in the pathogenesis of hypertension in end-stage renal failure.

Acetylcholine↗