Restoration of Acutely Thrombosed Arterio-Venous Fistulae by rTPA and Percutaneous Angioplasty

Acute thrombosis in native arterio-venous fistulae (AVF) results in considerable patient morbidity. Interventional radiology (IR) comprising thrombolysis and percutaneous transluminal angioplasty (PTA) is well established in the management of thrombosed polytetrafluoroethylene (PTFE) grafts. However its role in thrombosed AVF is uncertain. We looked retrospectively at the role of IR in re-establishing blood flow in acutely thrombosed AVF.

Between 1992–2000, 21 episodes of acutely thrombosed AVF in 15 patients (9 females; age range 29–80yrs) were referred for intervention. All fistulae were being used for haemodialysis at the time. Diagnosis was established by angiography and thrombolysis with recombinant tissue plasminogen activator (rTPA) was attempted in all patients. Discrete stenoses when present (n=12) were then treated with PTA and resistant or recurrent stenoses were managed by stent insertion (n=3). Patients were then heparinised for 24 hours.

Technical success as defined by radiological patency was achieved in 86% cases. Clinical success i.e. the ability to reuse of the fistula for haemodialysis was achieved in 62% of the interventions, where patency rates at 3 and 6 months were 92% and 69% respectively. Five patients had recurrence of thrombosis >3 months after the primary procedure, 3 had successful re-intervention. Minor local bleeding was the only complication.

Our retrospective study shows rTPA and PTA is successful in the management of acutely thrombosed AVF. We advocate the routine use of IR as a valuable technique for prolonging the life of native AVF in patients on maintenance haemodialysis.

Solid and papillary epithelial neoplasm of the pancreas: MR imaging findings

We present the magnetic resonance imaging (MRI) findings in a young patient with histological proven solid and papillary epithelial neoplasm of the pancreas. Although the appearance of this tumor at MRI can be useful in making a correct preoperative diagnosis, only few cases describing its MRI features have been reported in the radiological literature.

Disordered eating, body mass, and glycemic control in adolescents with type 1 diabetes

OBJECTIVE

To examine the relationship between disordered eating attitudes and behaviors, BMI, and glycemic control in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In a cross-sectional design, 152 adolescents (ages 11-19 years) completed three scales from the Eating Disorders Inventory (EDI): Body Dissatisfaction, Drive for Thinness, and Bulimia. All subjects had diabetes for > 1 year. Glycemic control was assessed by glycosylated hemoglobin (HbA1c). Height and weight were measured to assess BMI.

RESULTS

Adolescents with type 1 diabetes did not report more disordered eating attitudes and behaviors than the normative comparison sample. Male subjects with type 1 diabetes reported fewer symptoms of bulimia and female subjects with type 1 diabetes reported greater body satisfaction than the normative group. A higher BMI was a significant predictor of greater body dissatisfaction, more so for female than male subjects. Symptoms of bulimia were associated with older adolescence and female sex. Those with more symptoms of bulimia were also more likely to have a higher BMI. Sex (female) and body dissatisfaction (more dissatisfied) predicted a stronger desire to be thin. Longer duration of disease, more symptoms of bulimia, and obesity all predicted poorer glycemic control.

CONCLUSIONS

Female patients aged 13-14 years seem to be at greatest risk for developing disordered eating patterns. Using the clinical cutoff score (> or = 5) of the EDI Bulimia subscale as a screener in diabetes clinics may help identify adolescents whose disordered eating patterns are likely to compromise their glycemic control.

A prospective study of central venous hemodialysis catheter colonization and peripheral bacteremia

BACKGROUND

Sepsis as a consequence of central venous hemodialysis catheter colonization is a major cause of morbidity in the hemodialysis population. We have previously shown that the majority of catheters become colonized and that this is associated with peripheral bacteremia. The time period over which this colonization occurs is unknown.

METHOD

A prospective study of 31 central venous hemodialysis catheters was performed. Central venous blood cultures were taken from the catheter weekly after insertion. When the central cultures became positive, indicating catheter colonization, peripheral venous blood cultures were taken during dialysis to detect peripheral bacteremia.

RESULTS

Twenty-one catheters (68%) became colonized before their removal for reasons other than infection (mean time to colonization 27 days, range 5-115 days). Eleven patients (35%) developed peripheral bacteremia with the same organisms (mean time from colonization to bacteremia 32 days, range 5-26 days). Bacteremia only occurred when blood drawn from the catheter cultured more than 3000 colony forming units per ml.

CONCLUSIONS

Bacterial colonization of central venous catheters often leads to bacteremia. The time between insertion and colonization is very variable, but is universally present after 16 weeks. The risk of subsequent bacteremia is related not only to time left in situ, but also the degree of colonization. Surveillance cultures would allow clinicians to detect colonization before bacteremia occurs and take preventative measures.

Evolution of IgA nephropathy into Henoch-Schoenlein purpura in an adult

IgA nephropathy (IgAN) and Henoch-Schoenlein purpura (HSP) are clinically distinct conditions indistinguishable on renal biopsy. However, progression from IgAN to HSP has rarely been reported, particularly in adults. We report such a case: a young man with biopsy-proven IgAN and no systemic features of HSP who six years later developed classical HSP. This supports suggestions that the two conditions are different manifestations of the same disease.

Outreach services: issues and challenges

Tompkins-McCaw Library of Virginia Commonwealth University has planned and implemented four one-year outreach service projects during the past two years. These projects were funded by the National Library of Medicine and the National Network of Libraries of Medicine Southeastern/Atlantic Region. The projects focus on information access for public health nurses, HIV/AIDS information access, and circuit librarian services in rural Southern Virginia. This article documents issues and challenges which have been identified from these projects and suggests ways to resolve them.

Haemodialysis patients' knowledge and beliefs about medication

Patient adherence to treatment continues to concern health professionals. Non-adherence is costly to: a) the patient in terms of health, psychological well-being and quality of life, b) the health care providers in terms of individual professionalism, job satisfaction and the provision of optimum care packages, and c) the managers in terms of finance and service planning. Several factors are thought to be influential in treatment adherence.

Maintenance dialysis in a district general hospital

A programme of Continuous Ambulatory Peritoneal Dialysis has been in progress at the Gloucester Royal Hospital since January 1988. After 2 years patient and technique survival was 81% and 73% respectively, very similar to that in established British Renal Units. Management of end stage renal failure at the local District General Hospital has meant that patients no longer have to travel long distances to the Regional Renal Unit.

Prediction of carbon monoxide diffusing capacity of the lung in splenectomized sheep

The steady state diffusing capacity of the lung for carbon monoxide (DLCO) was studied in 18 splenectomized adult ewes. Seven animals were anemic when studied. Weight (Wt) and, to a lesser extent, hemoglobin (Hb) level were the key predictive variables of DLCO. Sheep DLCO can be expected to range between 15 and 28 ml/min/mmHg in adult ewes which are not anemic. When DLCO measurements were repeated up to three times on the same day no significant decreases occurred. Thus, the data demonstrated no CO back-pressure caused by preceding DLCO determinations. This paper's importance is in defining a normal predictive range for this sensitive parameter of pulmonary function.

Identification of the source of haematuria by automated measurement of red cell volume

The mean corpuscular volume (MCV) of urinary erythrocytes was measured by a Coulter Counter in 42 patients with asymptomatic haematuria. All patients had the source of haematuria established by a renal biopsy, cystoscopy or radiology. The mean urine MCV was significantly less in those with glomerular disease (n = 21) than in those with non-glomerular haematuria (n = 21). In every patient with glomerulonephritis, urinary erythrocytes were smaller than those in their own venous blood. Conversely, urinary red cells larger than venous blood were confined to patients with a non-glomerular source. Coulter analysis of urine provides a simple and objective aid to the diagnosis of haematuria.

Investigation of haematuria in adults

Haematuria, whether overt or microscopic has a wide range of causes and patients may present to a variety of clinicians. This article describes the modern approach to the investigation of haematuria and emphasizes the importance of cooperation between physicians and surgeons.

Pharmacokinetics of cefotetan in patients with end-stage renal failure on maintenance dialysis

The pharmacokinetics of a single intravenous dose of cefotetan were studied in 17 volunteer patients with end-stage renal failure, requiring intermittent haemodialysis in 12 cases or undergoing continuous ambulatory peritoneal dialysis in 5 cases. Between haemodialysis the mean plasma elimination half life was 20.4 h (S.E.M. +/- 2.1). This decreased to 7.5 h (S.E.M. +/- 0.6) during haemodialysis. In patients treated by continuous ambulatory peritoneal dialysis the mean plasma elimination half life was 15.5 h (S.E.M. +/- 1.9). Small amounts of cefotetan (5-9% of the administered dose) were recovered in the peritoneal dialysates removed over the 24 h following the dose.

A comparison of the uptake of human and porcine insulins given intraperitoneally to patients with diabetes mellitus on continuous ambulatory peritoneal dialysis

Intraperitoneal absorption of human insulin (crb) and porcine insulin was examined in 9 diabetic patients with renal failure, and on Continuous Ambulatory Peritoneal Dialysis (CAPD). Serial blood sampling was performed to determine the characteristics of insulin absorption and glycaemic control. Four patients received successive equal doses of human and porcine insulins, 2 received different doses and 3 received human insulin only. Glycaemic control was similar after both insulins. Mean insulin levels were consistently higher after human insulin with significant differences at 90, 300 and 360 min. It is concluded that, if required, patients may be transferred from i.p. purified porcine to i.p. human insulin without a change in insulin dose.

Home monitoring of blood pressure. Comparison of once daily morning measurements with those made throughout the day

Six subjects were investigated to establish whether self-recorded morning blood pressure is a reliable indicator of that taken throughout the day. After instruction, subjects recorded resting blood pressure on 6 successive mornings, and then hourly throughout the day. The morning pressures in each patient on each of the 6 days were very closely related to one another, with an overall mean of 157/102 mmHg (n = 36). Overall blood pressures throughout the day were not significantly different from the morning ones (158/100 mmHg, n = 88). Standard deviation for morning systolic blood pressure in each patient ranged from 4.5-8.4 compared with 3.8-10.4 mmHg for systolic blood pressure throughout the day. For diastolic blood pressure the ranges of standard deviation were 2.3-8.4 and 2.6-6.5 mmHg, respectively. No patient demonstrated a circadian rhythm. It seems that self-monitoring of blood pressure is reproducible and that the time of day that the measurement is made is unimportant, provided the patient is resting.

Effect of tuftsin on in vivo development of 3-methylcholanthrene-induced primary fibrosarcoma and Lewis lung carcinoma in mice

The effect of tuftsin therapy on tumor development was examined in a murine primary fibrosarcoma and the Lewis lung carcinoma systems. Following im injection of 3-methylcholanthrene (CAS: 56-49-5) on day 0, C57BL/10ScSn mice were treated weekly with 3 ip tuftsin injections beginning on day 1 or day 60. Similar patterns of tumor development were observed regardless of whether tuftsin therapy was immediate or delayed. Only modest differences in experimental and control tumor incidences were found upon termination of studies; however, treated animals developed significantly fewer tumors than controls early during the observation periods. Thus mean tumor latent periods varied significantly when therapy began on day 1 (103.6 days in controls vs. 119.1 in treated mice; P = .02) or 2 months later (104.6 days in controls vs. 115.3 in treated mice; P = .01). One day subsequent to intra-footpad implantation of 10(5) Lewis lung carcinoma cells, C57BL/6 mice received at least 10 iv injections of tuftsin and were compared with controls for variations in survival or lung tumor development. The mean survival time in treated mice, 41.2 days, differed sharply from that (30.1 days) in controls (P = .00001). Similar groups of mice varied significantly in mean metastatic lung colony counts when examined on day 30; there were 15.1 colonies in controls and 8.0 in experimental animals (P = .03).

Early experience and difficulties with bronchoalveolar lavage and transbronchial biopsy in the diagnosis of AIDS associated pneumonia in Britain

Bronchoalveolar lavage and transbronchial biopsy have been used as adjuncts to the management of patients with pneumonia associated with the acquired immunodeficiency syndrome (AIDS) at the Middlesex Hospital and the experience gained and difficulties encountered in the first five cases are reported. Widely varying organisms were isolated from lavage aspirates, some of which may have been nasopharyngeal contaminants, and organisms cultured from the transbronchial biopsy specimens may offer a better guide to antimicrobial treatment. Pneumocystis carinii was found in two of the patients. In view of the potentially serious toxicity of high dose co-trimoxazole, continuation of this treatment may be inadvisable if Pneumocystis carinii is not identified by all available methods unless there are strong clinical grounds to suspect its presence.

CAPD in end-stage renal amyloidosis

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Pulmonary function in insulin-dependent diabetes mellitus with limited joint mobility

Patients with insulin dependent diabetes mellitus (IDDM) and limited joint mobility (LJM) were studied to determine if altered respiratory mechanics were another manifestation of a generalized disturbance in collagen metabolism. Lung volumes and maximal expiratory flow volume curves were measured in 23 patients with IDDM. Patients were divided into 2 groups: (1) 11 without LJM, and (2) 12 with severe LJM. The groups were matched for age, sex, and glycemic control but not for duration of IDDM. In patients with severe LJM, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were significantly decreased (p less than 0.05). Total lung capacity (TLC), thoracic gas volume (TGV) at functional residual capacity (FRC) and residual volume (RV) were also significantly lower (p less than 0.05) in the severe LJM group. There was no evidence of air-flow obstruction in either group. Our results demonstrate an association between severe LJM and a significant decrease in lung volumes. This could be due to decreased lung compliance or restriction of chest wall expansion.

Pneumococcal pneumonia with bacteraemia

Fourteen cases of pneumococcal pneumonia with bacteraemia have been studied. Thirteen of the patients were older than 50 years and in ten there was evidence of pre-existing disease. Pneumococci of six serotypes were responsible for these infections but type 3 was the commonest and was associated with three of the four fatal cases. The patients who died all had evidence of renal failure. Eight of the ten survivors had prerenal failure which responded to treatment. Hyponatraemia was a common finding. Despite prompt antibiotic treatment and intensive therapy there is still a high morbidity and mortality from this condition.

Renal biopsy in the elderly: clinicopathological correlations in 143 patients

The clinical presentation and spectrum of renal histopathology is described in 143 patients aged 60 years or more, with renal disease. In 82 patients renal biopsy revealed primary renal disease. In the remainder, changes associated with systemic conditions were found. These included amyloidosis, polyarteritis nodosa and hypertension. Fifty patients present with the nephrotic syndrome, one third of whom had a membranous glomerulonephritis on the renal biopsy. Three patients had a carcinoma associated with this renal histology. Two patients had a minimal change lesion and their nephrotic syndrome responded to corticosteroids. Renal biopsies from the 45 patients present with renal failure revealed a variety of histopathology which included idiopathic crescentic nephritis and antiglomerular basement membrane disease. Percutaneous renal biopsy is a valuable diagnostic aid in elderly patients with renal disease.

[Moderate supplementation of potassium in essential hypertension]

23 unselected patients with mild to moderate essential hypertension, whose average supine blood pressure after two months' observation on no treatment was 154/99 mm Hg, were entered into an eight week double blind randomised crossover study of one month's treatment with slow release potassium tablets (60 mmol/day) versus placebo without alteration of dietary sodium or potassium intake. By the fourth week mean supine blood pressure had fallen by 4% on potassium supplementation compared with placebo. Urinary potassium excretion increased from 62 +/- 4.7 mmol/24 h on placebo to 118 +/- 7.4 mmol/24 h on potassium. The fall in blood pressure was not related to urinary sodium excretion before entry to the trial or while on placebo. Moderate potassium supplementation caused a small but significant fall in blood pressure in patients with mild to moderate essential hypertension and could be additive to the effects of moderate sodium restriction. This increase in potassium intake could be achieved with a potassium-based salt substitute and a moderate increase in vegetable and fruit consumption. Moderate dietary sodium restriction with dietary potassium supplementation may obviate or reduce the need for drug treatment in some patients with mild to moderate hypertension.

Continuous ambulatory peritoneal dialysis in systemic amyloidosis and end-stage renal disease

Three patients with end-stage renal failure complicating systemic amyloidosis have been treated with continuous ambulatory peritoneal dialysis for periods of 10, 14 and 18 months respectively. In each case satisfactory control of uraemia and fluid balance has been achieved.

Evidence that patients with Addison's disease are undertreated with fludrocortisone

Ten patients with Addison's disease, nine with undetectable plasma aldosterone, were found to be sodium and water depleted with high levels of plasma-renin activity despite receiving 0.05-0.1 mg/day of fludrocortisone and optimum doses of glucocorticoid replacement therapy. Fludrocortisone was withdrawn while patients were in hospital on a fixed sodium intake. There was an immediate natriuresis with a further increase in plasma-renin activity. When a daily dose of 0.3 mg of fludrocortisone was given all patients retained sodium and water and gained weight. There was a fall in plasma-renin activity in all patients and an associated fall in blood urea and plasma potassium, and an increase in plasma volume; oedema developed in some patients. At outpatient follow-up, the dose of fludrocortisone was adjusted according to plasma-renin activity. Most patients required 0.2 mg of fludrocortisone to maintain adequate sodium and water balance. These results suggest that patients with Addison's disease on 0.05-0.1 mg of fludrocortisone with undetectable plasma aldosterone levels are currently being undertreated with fludrocortisone. The best way of assessing sodium balance in these patients and their response to fludrocortisone is by measurement of plasma-renin activity in conjunction with 24 h urinary sodium excretion.

Glomerulonephritis, non-Hodgkin's lymphoma and leucocytoclastic vasculitis

2 cases of active focal proliferative glomerulonephritis, lymphocytic malignant lymphoma and leucocytoclastic vasculitis are described. 1 presented with the nephrotic syndrome and progressive renal impairment, the other with acute renal failure. Cryoglobulins were detected in the serum of 1 patient, but not in that of the other. Initial renal and skin biopsies in the 2 patients were strikingly similar. As well as demonstrating glomerular lesions, the renal biopsies contained interstitial lymphomatous infiltrate which, in 1 case, was initially incorrectly interpreted and resulted in delay in specific treatment. Immunosuppressive therapy markedly improved renal function and induced remission of the vasculitis and lymphoma. Repeat renal biopsy in 1 case confirmed regression of the glomerulonephritis. A common immunological aetiology may explain the co-existence of these three conditions in the 2 patients.

Lack of effect of beta-blocker on flat dose response to thiazide in hypertension: efficacy of low dose thiazide combined with beta-blocker

Increasing the dose of a thiazide diuretic used alone in patients with essential hypertension has little further effect on blood pressure but increases the deleterious metabolic consequences of the diuretic. The effect of a beta-blocker on this flat dose response is not known. In two randomised crossover studies the effect of 12.5 mg, 25 mg, and 50 mg hydrochlorothiazide combined with 400 mg acebutolol was assessed. The mean fall in supine blood pressure was about 15% and was the same whatever dose of thiazide was used with the beta-blocker. As the dose of hydrochlorothiazide was increased, however, there was evidence of increasing metabolic consequences of the diuretic. The study did not define the minimum dose of diuretic, and doses of hydrochlorothiazide lower than 12.5 mg might be as effective. These results suggest that many patients who are being treated with a combination of a beta-blocker and a diuretic are receiving unnecessarily large amounts of the diuretic without benefit to their blood pressure and with adverse metabolic consequences.

Dose-dependent effects of meclofenamate on peripheral vasculature of conscious rabbits

1. Changes in systemic haemodynamics and organ blood flow were measured in conscious rabbits after various doses of intravenous sodium meclofenamate, an inhibitor of prostaglandin cyclo-oxygenase. 2. Meclofenamate had no effect on arterial pressure or cardiac output but caused a dose-dependent fall in renal blood flow. 3. Meclofenamate also reduced adrenal perfusion but, in contrast, caused a dose-dependent increase in blood flow to the brain, bronchial and hepatic circulation and to the testis. No effect was demonstrated on other organs studied. 4. The effect on the cerebral circulation was observed at the lowest dose of meclofenamate (0.75 mg/kg). Higher total doses were necessary for an effect on the renal and bronchial (3 mg/kg) and testicular and hepatic arteries (6 mg/kg). 5. The results suggest a variety of local vasomotor influences of renal and non-renal prostaglandins in conscious rabbits.

Endralazine in patients with severe hypertension and renal insufficiency

Endralazine, a new peripheral vasodilator, was given in conjunction with a beta-blocker to 21 patients with hypertension and chronic renal failure. All subjects were either poorly controlled on their previous antihypertensive regime or were experiencing unacceptable adverse effects from drugs. After 4 weeks blood pressure was reduced in all patients and symptomatic side effects were few. Two patients became anti-nuclear factor (ANF) positive in weak titre but without evidence of the lupus syndrome.

Duration of action of meclofenamate on haemodynamics in conscious rabbits

1. The time dependent effects of intravenous sodium meclofenamate (6 mg/kg) on blood flow to a variety of organs was studied in the conscious rabbit. 2. After meclofenamate administration, blood flow was reduced in the kidney and adrenal glands and increased in the hepatic artery. The changes were relatively short lived and had disappeared by 30 min in the kidney and 60 min in the adrenal gland. 3. Cerebral vascular resistance was decreased after meclofenamate in the absence of any change in arterial acid-base balance. 4. A physiological effect of vasodilator prostaglandins on adrenal and splanchnic beds, in addition to the previously reported actions on the kidney, is suggested. Cerebral vasodilation following meclofenamate may indicate a dominant action of vasoconstrictor prostanoids in the brain. 5. The importance of timing of haemodynamic measurements after short term infusions of meclofenamate is demonstrated.

Moderate potassium supplementation in essential hypertension

23 unselected patients with mild to moderate essential hypertension, whose average supine blood pressure after two months' observation on no treatment was 154/99 mm Hg, were entered into an eight week double blind randomised crossover study of one month's treatment with slow release potassium tablets (60 mmol/day) versus placebo without alteration of dietary sodium or potassium intake. By the fourth week mean supine blood pressure had fallen by 4% on potassium supplementation compared with placebo. Urinary potassium excretion increased from 62 +/- 4.7 mmol/24 h on placebo to 118 +/- 7.4 mmol/24 h on potassium. The fall in blood pressure was not related to urinary sodium excretion before entry to the trial or while on placebo. Moderate potassium supplementation caused a small but significant fall in blood pressure in patients with mild to moderate essential hypertension and could be additive to the effects of moderate sodium restriction. This increase in potassium intake could be achieved with a potassium-based salt substitute and a moderate increase in vegetable and fruit consumption. Moderate dietary sodium restriction with dietary potassium supplementation may obviate or reduce the need for drug treatment in some patients with mild to moderate hypertension.

Xipamide and cyclopenthiazide in essential hypertension--comparative effects on blood pressure and plasma potassium

1 The blood pressure lowering effect of xipamide, a non-thiazide diuretic given for 6 weeks was compared in a randomised cross-over trial with that of cyclopenthiazide in 14 patients with essential hypertension. 2 Xipamide 10 or 20 mg given once daily was as effective in lowering supine blood pressure as daily cyclopenthiazide 0.5 mg. There was no difference in the blood pressure lowering effect of 10 mg xipamide daily for 2 weeks compared to 20 mg daily given for a further 4 weeks. 3 Plasma potassium was reduced by both drugs, but markedly more after both 10 mg and 20 mg xipamide than after cyclopenthiazide 0.5 mg. By the sixth week of treatment 13 of 14 patients on xipamide but only 6 of 14 on cyclopenthiazide has plasma potassium concentrations of, or less than, 3.5 mmol/l. The fall in plasma potassium was significantly greater and the final plasma potassium concentration was significantly lower after either dose of xipamide than after cyclopenthiazide. 4 These results suggest that 10 mg or 20 mg of xipamide daily is effective in lowering blood pressure in hypertensive patients but is associated with hypokalaemia. In view of recent evidence linking diuretic-induced hypokalaemia with cardiac dysrhythmias in patients with essential hypertension we would suggest that thiazide diuretics be used in preference to xipamide for the routine management of essential hypertension. Our results also suggest that the currently recommended dose of xipamide (20 mg) for the treatment of hypertension is excessive, and lower amounts than 10 mg per day might possibly be as effective in lowering blood pressure with less adverse metabolic consequences.

Effects of meclofenamate and captopril on adrenal blood flow: contrasts in conscious rabbits at rest and after hemorrhage

The role of prostaglandins and angiotensin II or kinins in maintaining adrenal blood flow was studied using the prostaglandin cyclo-oxygenase inhibitor meclofenamate and the kininase inhibitor captopril in resting and hemorrhaged (10 ml/kg) conscious rabbits. Meclofenamate (6 mg/kg intravenously) reduced adrenal blood flow after 3, 15 and 30 minutes by 26, 28 and 17 percent, respectively. Captopril increased adrenal flow by 20 percent, an effect subsequently reversed by meclofenamate. In contrast, hemorrhaged rabbits maintained adrenal blood flow following meclofenamate and captopril despite substantial reductions in renal blood flow with meclofenamate given before and after captopril. It is concluded that (1) adrenal blood flow at rest is modulated by vasodilator prostaglandins and to a lesser extent angiotensin II or bradykinin. (2) The adrenal effects of meclofenamate and captopril are overriden by hemorrhage, perhaps reflecting the need to increase adrenal hormones during hypovolemic stress. (3) The decrease in plasma catecholamines seen with meclofenamate at rest may be due to reduced adrenal blood flow.

Captopril in essential hypertension; contrasting effects of adding hydrochlorothiazide or propranolol

Twenty-four patients with moderate to severe hypertension were treated for four weeks with captopril, an oral inhibitor of angiotensin-converting enzyme. The fall in blood pressure with captopril alone correlated with pretreatment plasma renin activity. The effect of adding either hydrochlorothiazide or propranolol to the captopril treatment was then studied. The addition of hydrochlorothiazide to captopril produced a dose-dependent fall in blood pressure. At the higher dose of the diuretic this fall in blood pressure correlated with weight loss, suggesting that when the diuretic-induced compensatory rise in angiotensin II is prevented by captopril the fall in blood pressure becomes dependent on loss of sodium and water. In contrast, the addition of propranolol to captopril produced no further fall in blood pressure, suggesting that inhibition of angiotensin-converting enzyme prevents the blood pressure lowering effect of propranolol. This may have implications for the mechanism whereby beta-blockers alone lower blood pressure. These contrasting effects of hydrochlorothiazide and propranolol in the presence of captopril indicate that in patients whose hypertension is not controlled by captopril alone the addition of increasing doses of diuretic is likely to control the blood pressure. The addition of a beta-blocker, however, is less likely to be effective.

Effects of meclofenamate and captopril on renal and other regional vascular beds after mild haemorrhage in conscious rabbits

1. The role of prostaglandins and angiotensin II in blood flow regulation was studied in conscious rabbits subjected to mild haemorrhage. 2. Haemorrhage caused a 13% fall in arterial pressure and a 21% fall in cardiac output, responses which were unchanged by sodium meclofenamate, an inhibitor of prostaglandin synthesis, or captopril, an inhibitor of the angiotensin converting enzyme. 3. Haemorrhage doubled plasma adrenaline and noradrenaline levels. Plasma renin activity trebled after haemorrhage and was further elevated by captopril. 4. Renal blood flow was maintained after haemorrhage alone. Meclofenamate given immediately after haemorrhage caused a 31% fall in renal blood flow. Captopril given immediately after haemorrhage caused renal vasodilation, but when given after meclofenamate augmented renal vasoconstriction. 5. Splenic vasoconstriction was seen after haemorrhage and meclofenamate, and subsequently was augmented by captopril. 6. Results suggest that prostaglandins variably modulate regional blood flow in conscious rabbits subjected to mild haemorrhage. Enhanced sympatho-adrenal activity increases renovascular and splenic dependence on vasodilator prostaglandins, but not that of coronary, cerebral, hepatic or adrenal circulations. Renal and splenic vasoconstriction seen with meclofenamate are not due to circulating angiotensin II.

Effects of meclofenamate and captopril on blood flow to the kidney and spleen in conscious rabbits subjected to mild haemorrhage

1. Regional haemodynamic responses to mild haemorrhage were studied in three groups each of seven conscious rabbits, in the presence of either buffer, the prostaglandin cyclo-oxygenase inhibitor meclofenamate, or the kininase II inhibitor captopril. 2. Renal and splenic vasoconstriction occurred with meclofenamate in haemorrhaged animals, and were accentuated by the subsequent administration of captopril. 3. Captopril alone caused mild renal vasodilatation, but subsequent administration of meclofenamate again caused vasoconstriction. 4. Flow to the adrenal coronary, cerebral and hepatic artery circulations was unaffected by meclofenamate or captopril after haemorrhage. 5. The results indicated that the enhanced vasopressor activity occurring during haemorrhage greatly increased the dependence on vasodilator prostaglandins of flow to the renal and splenic vascular beds. 6. The vasoconstrictor effect of meclofenamate does not appear to be due to unopposed action of angiotensin II when prostaglandin synthesis is suppressed.

The effects of meclofenamate, captopril and phentolamine on organ blood flow in the conscious rabbit

1. Systemic and regional vascular changes were measured in conscious rabbits after intravenous sodium meclofenamate, captopril and phentolamine. These drugs were used respectively to inhibit prostaglandin synthesis and angiotensin-converting enzyme, and to block alpha-adrenoceptors. 2. Meclofenamate reduced renal and adrenal blood flow by 11 and 28% respectively, and doubled hepatic artery flow. The effect on renal and adrenal flow persisted in the presence of phentolamine. 3. Captopril decreased estimated peripheral resistance and increased cardiac output without changing arterial pressure. Kidney and adrenal flow increased by 70 and 21% respectively. 4. Phentolamine reduced arterial pressure and doubled flow to skeletal muscle and increased hepatic artery flow to the liver. 5. Splenic blood flow was unaffected by meclofenamate, captopril or phentolamine alone. Meclofenamate given after captopril caused a halving of splenic flow and a rise in arterial pressure; these effects were prevented by phentolamine. 6. The results point to a continuing effect of prostaglandin synthesis in maintaining blood flow to the kidney and adrenal gland independent of alpha-adrenoceptor activation in resting conscious rabbits. An important modulating effect of prostaglandins on sympathetic vascular tone in the spleen is suggested.