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S Carney

Publications and source records attributed to S Carney.

At least 19 recordsLinked to original sources

Lithium versus antidepressants in the long-term treatment of unipolar affective disorder.

BACKGROUND: The main rationale for the use of lithium in the long-term treatment of unipolar affective disorder is its efficacy in treating bipolar affective disorder and resistant depression. However, there is considerable uncertainty about which pharmacological intervention is most effective in the long-term treatment of recurrent unipolar affective disorder. OBJECTIVES: To assess the effects of lithium versus antidepressants for the long-term treatment of recurrent affective disorder. SEARCH STRATEGY: We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Registers (CCDANCTR-Studies and CCDANCTR-References) on 2/9/2005. Reference lists of relevant papers and major textbooks of affective disorder were checked. Experts in the field and pharmaceutical companies were contacted regarding unpublished material. SELECTION CRITERIA: Randomised controlled trials comparing lithium against antidepressant medication for the long-term treatment of patients with a diagnosis of affective disorder. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We collected adverse effects information from the trials. MAIN RESULTS: Eight trials involving 475 people were included. Two of the studies included a mixed group of participants with either bipolar or unipolar disorder. Relapse was defined as admission to hospital and when all kinds of relapses were considered (both depressive and manic), there was a statistically significant difference in favour of lithium (relative risk (RR) fixed effect 0.34, 95% CI 0.14 to 0.82). The results did not exclude the point of no effect, when the random-effects model was used (RR random effects 0.40, 95% CI 0.14 to 1.18). There were no other statistically significant differences between lithium and antidepressants according to all other outcomes considered. Manic or depressive relapse was defined as prescription of non-study medication for mood disorder, manic or depressive relapse (as defined by the study authors), quality of life, social functioning, occupational functioning, overall drop-out rate, drop-out rate due to side-effects, troublesome side-effects, mortality due to all causes and specifically suicides. AUTHORS' CONCLUSIONS: There was adequate efficacy evidence for lithium or antidepressants preventing relapse in unipolar affective disorder, however their relative efficacy was unknown. When considering lithium or antidepressant long-term therapy, patients and clinicians should take into account the patient's clinical history, the side-effects and the individual's likely adherence to the recommended treatment regime. Large-scale, long-term randomised trials in unselected groups of subjects with unipolar affective disorder are needed.

Antidepressive Agents↗

Growth and the premature baby.

There is considerable evidence to show that babies born prematurely have poor postnatal growth, and the more premature the baby, the greater the impairment is likely to be and the longer it will persist. Nutrition has been shown to play an important part in this, but adequate nutrition is difficult, if not impossible, to achieve in these infants. In the most immature infants, growth retardation may continue for many months and catch-up may be delayed and incomplete. Evidence from long-term studies suggests that preterm infants will be shorter and lighter than term controls and that reduced stature and head size may be linked with lower intelligence. Although there is evidence linking better growth to better neurodevelopmental outcome, with reports suggesting that this can be achieved with dietary manipulation, there are also data that suggest that there could be a link between increased postnatal growth and increased morbidity and mortality in later childhood and adult life. Here, we provide an overview of current understanding of growth impairment in infants born prematurely and the effects in later life.

Body Size↗

The effects of growth hormone treatment on health-related quality of life in children.

BACKGROUND/AIMS: The effects of growth hormone deficiency (GHD) on linear growth in children are well documented, but there is less convincing evidence regarding the impact on health-related quality of life (QOL). We examined QOL in children aged 8-16 years with acquired GHD following treatment for malignancy (AGHD) or idiopathic GHD (IGHD) on commencing growth hormone treatment (GHT) over 6 months. We adopted a longitudinal design involving consecutive patients and their families attending clinic over an 18-month period. Mothers and children were invited to complete questionnaires before GHT (T1) and 6 months later (T2). METHODS: Mothers of 22 children (AGHD n = 14; IGHD n = 8) completed standardized measures of child QOL and behaviour. Children completed parallel measures of QOL, short-term memory tasks and fitness either in clinic or at the family home. RESULTS: For children with AGHD, QOL was significantly below population norms at T1 and improved over time. For children diagnosed with IGHD, QOL at T1 was below, but comparable with population norms. QOL improved over time, though not significantly. CONCLUSION: GHT is potentially valuable for improving QOL in children, especially in cases of AGHD. We conclude that benefits of GHT for QOL need to be evaluated independent of different diagnostic groups.

Adolescent↗

Arm position and blood pressure: an audit.

Although arm position significantly alters blood pressure, this aspect of clinical behaviour has not been evaluated. Consequently, an audit of arm position preference involving 182 clinicians including physicians, general practitioners and nurses was performed. A marked variation in standing and sitting arm position preference, both between and within the three groups, was recorded, although approximately two-thirds of clinicians preferred the same arm position in the standing and sitting position. In particular, only 8 and 4% of clinicians chose the horizontal arm position in sitting and standing subjects, respectively. Choosing the dependent arm is a behaviour likely to lead to the overdiagnosis of hypertension and inappropriate treatment of hypertension because the dependent arm falsely elevates both systolic and diastolic blood pressure. These results should encourage national and international organizations to reaffirm the importance of the horizontal arm in the measurement of blood pressure.

Arm↗

Folate for depressive disorders.

BACKGROUND: There are a number of effective interventions for the treatment of depression. It is possible that the efficacy of these treatments will be improved further by the use of adjunctive therapies such as folate. OBJECTIVES: 1. To determine the effectiveness of folate in the treatment of depression 2. To determine the adverse effects and acceptability of treatment with folate. SEARCH STRATEGY: The Cochrane Controlled Trials Register (CCTR), and the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register (CCDANCTR) incorporating results of group searches of EMBASE, MEDLINE, LILACS, CINAHL, PSYNDEX and PsycLIT were searched. Reference lists of relevant papers and major textbooks of affective disorder were checked. Experts in the field and pharmaceutical companies were contacted regarding unpublished material. SELECTION CRITERIA: All randomised controlled trials that compared treatment with folic acid or 5'-methyltetrahydrofolic acid to an alternative treatment, whether another antidepressant medication or placebo, for patients with a diagnosis of depressive disorder (diagnosed according to explicit criteria). DATA COLLECTION AND ANALYSIS: Data were independently extracted from the original reports by two reviewers. Statistical analysis was conducted using Review Manager version 4.1. MAIN RESULTS: Three trials involving 247 people were included. Two studies involving 151 people assessed the use of folate in addition to other treatment, and found that adding folate reduced Hamilton Depression Rating Scale scores on average by a further 2.65 points (95% confidence interval 0.38 to 4.93). Fewer patients treated with folate experienced a reduction in their HDRS score of less than 50% at ten weeks (relative risk (RR) 0.47, 95% CI 0.24 to 0.92) The number needed to treat with folate for one additional person to experience a 50% reduction on this scale was 5 (95% confidence interval 4 to 33). One study involving 96 people assessed the use of folate instead of the antidepressant trazodone and did not find a significant benefit from the use of folate. The trials identified did not find evidence of any problems with the acceptability or safety of folate. REVIEWER'S CONCLUSIONS: The limited available evidence suggests folate may have a potential role as a supplement to other treatment for depression. It is currently unclear if this is the case both for people with normal folate levels, and for those with folate deficiency.

Antidepressive Agents↗

Arm position and blood pressure: a risk factor for hypertension?

The objective of this study was to re-evaluate the effect of arm position on blood pressure (BP) measurement with auscultatory and oscillometric methods including ambulatory blood pressure monitoring (ABPM). The setting was the hospital outpatient department and the subjects chosen were normotensive and hypertensive. The effect of lowering the arm from heart level on indirect systolic BP (SBP) and diastolic BP (DBP) measurement as well as the importance of supporting the horizontal arm were measured. In the sitting position, lowering the supported horizontal arm to the dependent position increased BP measured by a mercury device from 103+/-10/60+/-7 to 111+/-14/67+/-10 mmHg in normotensive subjects, a mean increase of 8/7 mmHg (P<0.01). In hypertensive subjects, a similar manoeuvre increased BP from 143+/-21/78+/-17 to 166+/-29/88+/-20 mmHg, an increase of 23/10 mmHg (P<0.01). Combined results from normotensive and hypertensive subjects demonstrate a direct and proportional association between BP (SBP and DBP) and the increase produced by arm dependency. Similar changes and associations were noted with oscillometric devices in the clinic situation. However, supporting the horizontal arm did not alter BP. Of particular interest, analysis of 13 hypertensive subjects who underwent ABPM on two occasions, once with the arm in the 'usual' position and once with the arm held horizontally for BP measurement during waking hours, demonstrated changes comparable to the other devices. The mean 12-hour BP was 154+/-19/82+/-10 mmHg during the former period and significantly decreased to 141+/-18/74+/-9 mmHg during the latter period (P<0.01). Regression analysis of the change in SBP and DBP with arm position change again demonstrated a close correlation (r(2)=0.8113 and 0.7273; P<0.001) with the artefact being larger with higher systolic and diastolic pressures. In conclusion, arm movements lead to significant artefacts in BP measurement, which are greater, the higher the systolic or diastolic pressure. These systematic errors occur when using both auscultatory and oscillometric (clinic and ABPM) devices and might lead to an erroneous diagnosis of hypertension and unnecessary medication, particularly in individuals with high normal BP levels. Since clinical interpretations of heart level vary, the horizontal arm position should be the unambiguous standard for all sitting and standing BP auscultatory and oscillometric measurements.

Adolescent↗

Recent advances in evidence-based psychiatry.

BACKGROUND: There is increasing interest in the potential contribution of evidence-based medicine to clinical decision making in psychiatry. In this article, we describe some of the recent advances in evidence-based psychiatry and outline future challenges. METHOD: Narrative review. CONTENT: The successful introduction of evidence-based practice into psychiatry requires the acquisition of new skills by clinicians. It is also important that policy statements that aim to be evidence-based, such as clinical practice guidelines, use rigorous methods to synthesize the primary evidence and do not overlook its limitations. One result of the systematic reviewing of evidence is the identification of important residual clinical uncertainties. Primary research can then be focused on these questions. For questions regarding therapy in psychiatry, it will be necessary to undertake some large, simple randomized trials. Making the best available evidence readily accessible in a clinical setting, however, remains a significant challenge. CONCLUSIONS: Collaboration between clinicians, researchers, policy-makers, and those involved in information technology is required to optimize the contribution of evidence-based medicine in psychiatry.

Culture↗

Neonatal and post-natal growth.

Growth velocity is higher in late intra-uterine and early post-natal life than at any time thereafter, and accurate measurements are essential for appropriate monitoring. The accuracy with which such measurements are made and recorded is frequently questionable, however, and short- and medium-term changes in growth may be difficult to interpret in the light of normal variations in the pattern of growth. Infants who are small at birth must be accurately classified because intra-uterine growth retardation and small for gestational age have different implications for both causation and outcome. Prediction of expected growth on the basis of mid-parental height is essential but frequently omitted. Post-natal growth impairment is common in pre-term infants and is often rapid in onset. Poor growth may continue for many months, and catch-up may be incomplete. Early growth failure may have a significant influence on subsequent morbidity and mortality.

Aging↗

Which clinical anesthesia outcomes are important to avoid? The perspective of patients.

UNLABELLED: Healthcare quality can be improved by eliciting patient preferences and customizing care to meet the needs of the patient. The goal of this study was to quantify patients' preferences for postoperative anesthesia outcomes. One hundred one patients in the preoperative clinic completed a written survey. Patients were asked to rank (order) 10 possible postoperative outcomes from their most undesirable to their least undesirable outcome. Each outcome was described in simple language. Patients were also asked to distribute $100 among the 10 outcomes, proportionally more money being allocated to the more undesirable outcomes. The dollar allocations were used to determine the relative value of each outcome. Rankings and relative value scores correlated closely (r2 = 0.69). Patients rated from most undesirable to least undesirable (in order): vomiting, gagging on the tracheal tube, incisional pain, nausea, recall without pain, residual weakness, shivering, sore throat, and somnolence (F-test < 0.01). IMPLICATIONS: Although there is variability in how patients rated postoperative outcomes, avoiding nausea/vomiting, incisional pain, and gagging on the endotracheal tube was a high priority for most patients. Whether clinicians can improve the quality of anesthesia by designing anesthesia regimens that most closely meet each individual patient's preferences for clinical outcomes deserves further study.

Adult↗

Acute lithium administration impairs the action of parathyroid hormone on rat renal calcium, magnesium and phosphate transport.

1. Chronic lithium (Li+) treatment commonly produces a state of hyperparathyroidism in humans and rat although the mechanism is unknown. 2. The present study evaluated the acute effect of Li+ on renal electrolyte transport, particularly Ca2+ and Mg2+ in thyroparathyroidectomized (TPTX) and intact rats. 3. The acute administration of Li+ significantly increased water, sodium, potassium and phosphate excretion in both TPTX and intact animals; however, Ca2+ and Mg2+ excretion was only increased in the intact group. Fractional excretion (FE) of Ca2+ and Mg2+ increased from 2.2 +/- 0.2 to 3.5 +/- 0.3% and 12 +/- 2 to 18 +/- 2%, respectively (P < 0.01). 4. In further experiments in TPTX rats, Li+ administration inhibited the usual reduction in urine Ca2+ and Mg2+ excretion following parathyroid hormone (PTH) administration and inhibited the phosphaturia. However, supramaximal concentrations of PTH overcame this inhibitory effect. For example, an FECa of 3.8 +/- 0.2% was reduced to 1.4 +/- 0.2% and 1.7 +/- 0.2% with maximal and supramaximal PTH concentrations, respectively, while in the presence of Li+ an FECa of 4.0 +/- 0.2 was decreased to 2.8 +/- 0.2 and then 1.9 +/- 0.3% with the same PTH concentrations. 5. The inhibitory effect of Li+ was reduced with a lower plasma Li+ concentration (0.7 +/- 0.2 vs 1.6-1.8 mmol/L). The FEMg results were comparable. 6. These results demonstrate that Li+ directly inhibits PTH-mediated renal reabsorption of Ca2+ and Mg2+ and also blunts PTH-mediated phosphaturia. Therefore, the hyperparathyroidism in humans following Li+ treatment may be a consequence of reduced renal Ca2+ reabsorption.

Animals↗

Effect of diuretics on sodium and chloride permeability in the rat papillary collecting duct.

While in vivo data suggests that diuretics such as furosemide and hydrochlorothiazide alter inner medulla collecting duct (IMCD) cell electrolyte transport, this has not been confirmed by in vivo studies nor have the mechanisms been evaluated. This study evaluated the direct effect of these diuretics as well as amiloride on sodium and chloride unidirectional permeability in the isolated perfused rat IMCD. In the absence of diuretics, the permeability of sodium was lower than that of chloride (0.63 +/- 0.05 compared with 0.83 +/- 0.08 micrometer/s), although both were relatively impermeable when compared to water. Furosemide (10(-4)) and hydrochlorothiazide (10(-3)) both increased the diffusional permeability of chloride by approximately 30% (0.80 +/- 0.06 to 1.04 +/- 0.09 micrometer/s, p < 0.01, and 0.74 +/- 0.09 to 0.98 +/- 0.10 micrometer/s, p < 0.02, respectively). However, sodium permeability was unaltered. Inhibition of Na+, K+-ATPase by ouabain or cooling (4 degrees C) inhibited basal sodium but not chloride permeability while a maximal antidiuretic AVP concentration did not alter sodium or chloride permeability. However, increasing the lumen and bath sodium chloride concentration from 150 to 300 and 600 mM significantly increased both sodium and particularly chloride conductance. In contrast, amiloride (10(-4)) significantly reduced both sodium and chloride permeability. These studies support a direct effect of furosemide and hydrochlorothiazide on the IMCD and suggest that their in vivo effect is primarily mediated by facilitating the passive movement of chloride into the lumen via a favourable electrochemical gradient. These results also demonstrate that amiloride inhibits both sodium and chloride unidirectional permeability by mechanisms separate to that of the sulphonamide-related diuretics.

Amiloride↗

Antihypertensive effects of mibefradil in the treatment of mild-to-moderate systemic hypertension.

This report summarizes the results of 4 double-blind, placebo-controlled studies designed to determine the efficacy, tolerability, and dose-response characteristics of the novel T-channel-selective calcium antagonist, mibefradil, in the treatment of mild-to-moderate essential hypertension. Two of these studies were conducted in the general population of essential hypertensives, 1 in elderly patients, and 1 in patients on chronic hydrochlorothiazide treatment. A total of 1,116 patients were randomized to receive 1 of 7 doses of mibefradil (6.25-200 mg; n = 927), or placebo (n = 189). Each study demonstrated a significant linear dose response in the reduction of sitting diastolic (SDBP) and sitting systolic (SSBP) blood pressure. In all 4 trials, SDBP was significantly reduced with the recommended doses of 50 and 100 mg mibefradil (placebo-corrected treatment effects of -4.1 to -6.8 mm Hg and -8.8 to -11.1 mm Hg, respectively, for the 50- and 100-mg doses). A similar reduction in SSBP occurred in 3 of 4 studies at the 50-mg dose (-7.5 to -10.7 mm Hg) and in 4 of 4 studies at the 100-mg dose (-6.8 to -16.7 mm Hg). Lower doses did not reduce blood pressure significantly; doses > 100 mg had little additional effect and an increased incidence of adverse events. Overall, response and normalization rates were dose related and averaged 61% and 51%, respectively, for the 50-mg dose and 78% and 65%, respectively, for the 100-mg dose. The onset of the antihypertensive effect was gradual, with no first-dose effect; near maximal response was reached within 1-2 weeks. Trough/peak ratios ranged from 77-86% with the 50-mg dose and from 77-108% with the 100-mg dose, indicating a sustained effect over a 24-hour period. A slight decrease in heart rate was observed, ranging from -2.2 to -5.5 beats/min at the 50-mg dose and from -4.0 to -8.8 beats/min at the 100-mg dose. The efficacy and safety results were similar across all populations studied, including the elderly and hydrochlorothiazide-treated patients, indicating that no dose adjustment is needed for these populations. Thus, the results of these 4 placebo-controlled trials confirm that when taken at the recommended doses of 50 and 100 mg once daily, mibefradil is an effective, safe, and well-tolerated therapy for the treatment of mild-to-moderate hypertension.

Adolescent↗

Pro-haemorrhagic effects of calcium antagonists: a comparison of isradipine and atenolol on ex vivo platelet function in hypertensive subjects.

It has been suggested that long term treatment with calcium antagonist drugs might inhibit platelet function and lead to an anti-atheromatous effect. However recent data have also suggested that such an effect might increase mortality due to an increased incidence of gastrointestinal bleeding. We identified 43 subjects from general practice with uncomplicated mild to moderate hypertension to compare the effects of the calcium antagonist isradipine with that of the beta-blocker atenolol on platelet function, plasma beta-thromboglobulin levels, fibrinolysis, and serum lipids in a randomised double-blind parallel group study. After careful evaluation to exclude concomitant aspirin use, only 24 subjects were eligible to enter the study. While isradipine and atenolol produced comparable and clinically significant falls in blood pressure (167 +/- 2/102 +/- 1 to 153 +/- 3/91 +/- 2 mm Hg, and 165 +/- 2/101 +/- 1 to 156 +/- 4/91 +/- 2 mm Hg, respectively), neither drug produced a detectable effect on ex vivo platelet aggregation, platelet retention, or thromboxane generation with adrenaline, collagen, adenosine-di-phosphate, or platelet activating factor. However a decrease in plasma beta-thromboglobulin levels was observed which reached statistical significance (P < 0.05) after 12 weeks treatment in the isradipine but not the atenolol group. A 39% reduction with isradipine compared with 34% following atenolol treatment. Euglobulin clot lysis time was not altered by either drug. Serum cholesterol concentrations were also unaltered by drug treatment. Therapeutic doses of the calcium antagonist isradipine may produce a minor indirect effect on platelet function after several weeks of treatment. However, this is of doubtful clinical importance and may simply reflect an effect of lowered blood pressure on platelet function.

Adrenergic beta-Antagonists↗

The addition of mibefradil to chronic hydrochlorothiazide therapy in hypertensive patients is associated with a significant antihypertensive effect.

OBJECTIVE: To evaluate the antihypertensive efficacy, tolerability, safety, and dose-response characteristics of the novel calcium antagonist, mibefradil, in combination with a diuretic regimen. DESIGN: A multinational, double-blind, randomised, placebo-controlled, parallel-design trial. METHODS: Three hundred and seven patients whose mild-to-moderate essential hypertension remained uncontrolled after 4 weeks of treatment with hydrochlorothiazide (HCTZ) 25 mg/day and placebo were randomised to receive combined treatment with HCTZ and once-daily doses of 12.5, 25, 50, or 100 mg of mibefradil or placebo. After 8 weeks of combined treatment, HCTZ was withdrawn and the mibefradil groups continued on their respective doses for an additional 6 weeks. RESULTS: After 8 weeks, the addition of once-daily doses of mibefradil to the initial HCTZ regimen resulted in clinically relevant, dose-related reductions in sitting diastolic blood pressure (SDBP) and sitting systolic blood pressure (SSBP) at trough, which were significantly greater in the 50 and 100 mg dose groups compared to the placebo group (P < or = 0.003). Placebo-corrected treatment effects on SDBP and SSBP at the end of the combined treatment period relative to baseline were, respectively, -4.1 and -8.0 mm Hg in the 50 mg mibefradil group and -9.5 and -8.0 mm Hg in the 100 mg mibefradil group. Therapeutic response rates to combination mibefradil and HCTZ therapy were high and dose related, reaching 82% for SDBP in the 100 mg group. CONCLUSIONS: The addition of once-daily doses of 50 or 100 mg of mibefradil to patients whose hypertension is not controlled by HCTZ alone is well tolerated and effective in improving BP control.

Adult↗

Main results of the losartan versus amlodipine (LOA) study on drug tolerability and psychological general well-being. LOA Study Group.

OBJECTIVE: To compare two losartan regimens (with and without hydrochlorothiazide) and amlodipine in treating mild-to-moderate hypertension regarding their blood-pressure-lowering effect, drug tolerability and quality of life. DESIGN: A 12-week, randomized, double-blind, parallel-group, multi-centre study. After 4 weeks of placebo, patients with a diastolic blood pressure (DBP) in the range 95-115 mmHg were allocated randomly to be administered 50 mg losartan (increased to 100 mg if the DBP was 90 mmHg or more after 6 weeks), 50 mg losartan (plus 12.5 mg hydrochlorothiazide under the above conditions), or 5 mg amlodipine (increased to 10 mg under the above condition). The tolerability of the treatment and the quality of life were evaluated by spontaneous reporting, active questioning and the Psychological General Well-Being (PGWB) index. STUDY POPULATION: In total 898 hypertensives, mainly referred from primary health care (mean age 57.8 years) of whom 52% were men. RESULTS: Administration of 50 mg losartan (plus 12.5 hydrochlorothiazide if necessary) and of 5 mg amlodipine (or 10 mg if necessary) lowered the blood pressure as well as or better than did 50 mg losartan (or 100 mg if necessary). The incidence of 'any discomfort' and 'swollen ankles' increased with amlodipine but not with losartan treatment. The opposite was found for 'dizziness upon standing'. The incidence of drug-related adverse events and the number of patients withdrawn from therapy were higher with amlodipine than they were with losartan treatment. The PGWB index at week 12 indicated that improvements from baseline had occurred in some domains for the losartan groups whereas it remained unchanged for the amlodipine group. CONCLUSION: Both losartan and amlodipine were effective in lowering the blood pressure and were tolerated well. Administration of 50 mg losartan (plus 12.5 mg hydrochlorothiazide if necessary) and of 5 mg amlodipine (or 10 mg if necessary) lowered the blood pressure equally well or better than did 50 mg losartan (or 100 mg if necessary). Drug-related adverse effects and withdrawal from the study were more common for the amlodipine group. The clinical significance of the improvements in the PGWB index with losartan needs to be studied further.

Adult↗

The measurement of neonates.

Accurate measurements of both healthy and premature neonates are possible but rarely performed. Routine anthropometry is often not performed at all or with large measurement errors due to inadequate training of personnel or inappropriate equipment. Sick neonates are often considered unsuitable for anthropometry and growth is wrongly equated with weight gain. Gain in length may be disturbed by poor health and permanent extrauterine growth retardation and changes in body proportions induced in some survivors of neonatal intensive care. Drug treatments may have profound effects on length gain and the relationship of length to weight.

Anthropometry↗

The effect of adrenalectomy on water permeability in rat papillary collecting duct.

1. Chronic adrenal insufficiency impairs maximal urine concentration, probably in part due to reduced medullary tonicity but also possibly by inhibition of distal nephron water transport. This latter defect has been demonstrated in rabbit but not in rat. 2. Since the time between adrenalectomy and experiment was different in rabbit and rat studies, diffusional water permeability was evaluated in the papillary collecting duct in the absence and presence of submaximal (20 microU/mL) and supramaximal (200 microU/mL) arginine vasopressin (AVP) in adrenalectomized rats at 7, 14 and 21 days. 3. Experimentation 7 days after adrenalectomy failed to demonstrate significantly altered basal or AVP-induced water permeability which increased by 23 and 78% with submaximal and supramaximal concentrations, respectively. Submaximal AVP concentrations also induced a comparable change in water permeability in adrenalectomized rats at 14 days; however, 21 days after adrenalectomy, diffusional water permeability was not increased by 20 microU/mL AVP (3.31 +/- 0.22 to 3.31 +/- 0.24 microns/s). Nevertheless, the effect of a supramaximal AVP concentration (200 microU/mL) was not altered by adrenalectomy (4.54 +/- 0.39 to 8.08 +/- 0.96; P < 0.01). Incubation of collecting ducts in aldosterone for 2 h did not reverse the inhibitory effect of chronic adrenalectomy on AVP-stimulated water transport. 4. These studies suggest that mineralocorticoid withdrawal does impair the hydro-osmotic action of AVP in the rat papillary collecting duct but that this effect takes between 14 and 21 days to occur.

Adrenal Glands↗