Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

MR-proADM is a strong independent predictor of long-term all-cause mortality risk in patients with chronic heart failure: results from the E-INH study

Background

Mid-regional proadrenomedullin (MR-proADM) is a blood biomarker indicating critical illness. Its short-term prognostic relevance has been investigated in several conditions including heart failure (HF). Yet, the long-term prognostic utility is unknown.

Methods

We conducted a post-hoc analysis of the Extended Interdisciplinary Network for Heart Failure (E-INH) study, which investigated the long-term effects of a HF nurse-led remote patient care program (HeartNetCare-HFTM [HNC]). Patients from nine regional centers in Germany hospitalized with HF and a left ventricular ejection fraction (LVEF) &lt;40% were randomized into HNC vs. Usual Care. MR-proADM and other standard biomarkers for disease progression and systemic inflammation were measured from venous blood collected at study inclusion, i.e. during index hospitalization. The prognostic utility was assessed using Kaplan-Meier plots and Cox proportional hazard models, and compared with other biomarkers by ROC curves.

Results

From 919 out of the 1022 recruited patients (90%), baseline levels of MR-proADM were available: median MR-proADM 0.89 (quartiles 0.63, 1.28) nmol/l; mean age 68±12 years; 28% women; 45% in class III or IV of the New York Heart Association (NYHA) classification.

Median LVEF was 31 (25, 37) %. Median levels of NT-proBNP, high sensitive C-reactive protein (hsCRP), tumor necrosis factor (TNF)-a, and interleukin-6 (IL-6) were 3045 (1087, 7759) pg/ml, 9.2 (3.3, 25.2) mg/l, 13.4 (10.4, 17.5) pg/ml, and 4.9 (2.0, 11.4) pg/ml, respectively. Higher levels of MR-proADM at baseline were associated with age, female sex, NYHA class, NT-proBNP, hsCRP, IL-6, and TNF-α, while there was an inverse association with LVEF.

In the course of 10 years of follow-up, 691 (68%) patients died. Unadjusted MR-proADM strongly predicted all-cause death when used as a continuous variable (HR 1.31 per nmol/l, 95% CI 1.26–1.37; p&lt;0.001) or when grouped into quartiles (HR 1.85, 95% CI 1.71–2.0; p&lt;0.001). Adjustments for age, sex and NYHA functional class did not materially alter the strong association. Plotting quartiles of MR-proADM in a Kaplan-Meier curve (see Figure 1) confirmed this findings. As shown in Figure 2, MR-proADM had the highest area under the curve (AUC) in ROC analysis when compared to other biomarkers.

Conclusion

MR-proADM appears to be a strong and independent predictor for long-term all-cause mortality risk in HF with reduced ejection fraction (HFrEF). Therefore, assessing MR-proADM may contribute to better categorization of risk and tailored care. Its clinical utility needs to be investigated in future studies.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): BMBF

Distribution pattern of left ventricular ejection fraction in patients with decompensated heart failure depends on sex results of a latent class analysis

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): unrestricted grant from Boehringer Ingelheim

Background & Aims Since 2016, heart failure (HF) is classified using left ventricular ejection fraction (LVEF) thresholds of 40% and 50%. However, HF phenotypes may develop across the entire LVEF spectrum depending on individual patient characteristics including the risk and comorbidity profile. Using latent class analysis, we explored the sex-specific distribution of in-hospital LVEF in patients hospitalized for acute heart failure (AHF) at a tertiary care center in Germany.

Methods Consecutive patients (≥18 years) hospitalized for AHF were recruited and phenotyped prospectively on a 7/24 basis. Exclusion criteria were high output heart failure, cardiogenic shock, and being listed for high urgency cardiac transplantation. LVEF was determined by transthoracic echocardiography using Simpson´s biplane or monoplane method. First, we estimated the distribution of LVEF in both sexes using histogram and kernel density estimation methods (bandwidth was selected by biased cross-validation). Then, Gaussian Mixture Models were fitted with increasing number of components. To identify the optimal number of subgroups we calculated the Bayesian Information Criterion (BIC). The minimum of the BIC criterion suggests the optimal number of subgroups for the final model. This analysis was performed on subsets including only male and only female patients.

Results Out of 629 patients (39.8% female) admitted with AHF between 09/2014 and 12/2017, 93% patients received in-hospital echocardiography, and in 79.2% LVEF could be quantitatively assessed. The BIC suggested two subgroups each for male (Fig. A) and female patients (Fig. B). In the male two-subgroup model, mean ± SD LVEF values were 30 ± 9% and 59 ± 8%, thus covering 48% and 52% of the men, respectively (Fig. C). In the female two-subgroup model, respective LVEF values were 36 ± 13% and 65 ± 8%, thus covering 47% and 53% of patients (Fig. D). The "male" model suggested 45% as cut-point, whilst the "female" model suggested 51% as cut-point differentiating between lower and higher LVEF.

Conclusions Using non-parametric and parametric statistical approaches, specific subgroups of patients hospitalized with AHF were identified among male and female patients hospitalized for AHF, which each time comprised subgroups with impaired vs. more preserved LVEF. Future analyses in larger AHF cohorts as well as in populations with chronic stable HF are warranted which take also into consideration sex differences in HF aetiology.

Figure

A) Minimum number of components (BIC) in men. B) Minimum BIC in women. C) LVEF distribution in men (2 components). D) LVEF distribution in women (2 components). The orange line indicates the respective cut-points between low and high LVEF.

Abstract Figure.

Global wasted myocardial is unrelated to conventional markers of systolic and diastolic function in patients with acute heart failure

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The AHF Register is supported by an unrestricted grant of Behringer Ingelheim, and grants of the German Ministry of Research and Education within the Comprehensive Heart Failure Center, Würzburg (BMBF 01E01004 and 01E01504)

onbehalf

AHF Registry

Background & Aim Myocardial Work (MyW) analysis quantifies myocardial performance using non-invasively derived pressure-strain loops. It is considered less load-dependent than left ventricular ejection fraction (LVEF) and longitudinal strain, since it integrates blood pressure into the assessment. We assessed associations between MyW indices, natriuretic peptide (NT-proBNP), and conventional markers of systolic and diastolic cardiac function mirroring the hemodynamic changes occurring during hospitalization, in patients hospitalized for acute heart failure (AHF).

Methods Consecutive patients (≥18 years) hospitalized for AHF with serial high-quality pairs of echocardiograms (i.e., early after hospitalization and prior to discharge) were eligible. Exclusion criteria were high output AHF, cardiogenic shock, and being listed for high urgency transplantation. The following MyW measures [definition in brackets] were analyzed from the stored recordings: Global constructive work (GCW) [sum of positive work performed during systolic shortening plus negative work during lengthening in isovolumetric relaxation (IVR)], global wasted work (GWW) [sum of negative work performed during systolic lengthening plus work performed during shortening in IVR], global work efficiency (GWE) [constructive work/(constructive work + wasted work)]; global work index (GWI) [total work performed from mitral valve closure to mitral valve opening]. Associations were determined using scatter plots and Pearson Product-Moment correlation coefficients.

Results N = 126 patients (73 ± 12 years, 37% female) were eligible. GWI and GCW proved significantly correlated with surrogates measured both on admission and at discharge, NT-proBNP, LVEF, and e’ (Table). By contrast, GWW did not correlate with any of these variables. GWE was also correlated with NT-proBNP (and e’ at discharge), but at both time points respective correlations were more pronounced.

Conclusion In patients hospitalized for AHF, GWI, GCW and GWE were associated with conventional parameters of myocardial stress and LV dysfunction. In contrast, GWW was unrelated with any of these established markers. Future studies in larger cohorts and with longer-term follow-up need to clarify to what extent might GWW carry complementary clinical and prognostic significance.

Abstract Figure.

P803 Myocardial work in acutely decompensated heart failure patients differs between HFrEF and HFpEF

OnBehalf

AHF Registry

Background & Aim A novel echocardiographic method to non-invasively determine left ventricular (LV) myocardial work (MyW) based on speckle-tracking derived longitudinal strain and blood pressure has recently been validated against invasive reference measurements. MyW is considered less load-dependent than LV ejection fraction (EF) and LV longitudinal strain. We investigated MyW indices in patients with reduced ejection fraction (LVEF &lt;40%; HFrEF) and patients with preserved ejection fraction (LVEF ≥50%, HFpEF) admitted for acutely decompensated heart failure (AHF).

Methods The AHF registry is a monocentric prospective follow-up study that comprehensively phenotypes consecutive patients hospitalized for AHF. Echocardiography was performed on the day of admission. MyW assessment was performed off-line using EchoPAC (GE, version 202). Here we present MyW indices and performed two-sided t-tests to analyze differences in numerical baseline covariates.

Results We analyzed the echocardiograms of 94 AHF patients (72 ± 10 years; 36% female). 46 patients (49%) had an LVEF &lt;40%, while 48 patients (51%) presented with LVEF ≥50%. HFrEF patients were younger, less often female, and hat lower blood pressure (table). Consistent with lower LVEF, HFrEF patients had less negative global longitudinal strain and lower global constructive work, when compared to HFpEF patients. Since HFrEF patients also had higher global wasted work, this yielded a lower myocardial work efficiency compared to HFpEF patients (table).

Conclusions This analysis in patients with AHF exhibited marked differences in MyW indices according to subgroups with HFrEF and HFpEF, thus adding information to the classical measures of LV function. Future research has to determine whether constructive and/or wasted MyW are valuable diagnostic or therapeutic targets in patients with AHF.

Abstract P803 Figure.

P1432 Heart failure subgroups according to left ventricular ejection fraction A latent class analysis

Funding Acknowledgements

German Research Foundation (BMBF 01EO1004 and 01EO1504)

OnBehalf

AHF

Background & Aims Heart failure (HF) is classified according to left ventricular (LV) ejection fraction (EF) into heart failure with reduced (HFrEF) and heart failure with preserved EF (HFpEF). In 2016, a third subgroup, heart failure with mid-range EF (HFmrEF), has been introduced by the ESC. We aimed to identify the number of naturally occurring heart failure subgroups according to LVEF using latent class analysis.

Methods The AHF registry is a monocentric prospective follow-up study that comprehensively phenotypes consecutive patients hospitalized for acute heart failure (AHF). Echocardiography was performed within 72 hours prior to discharge. We first estimated the distribution of LVEF using histogram and kernel density estimation methods (bandwidth was selected by biased cross-validation). We then fitted Gaussian Mixture Models with increasing number of components to the data. To select the optimal number of components we calculated the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). The minimum of each criterion suggests the optimal number of components for the final model. The BIC requires more data to select more components than the AIC and hence is more conservative. Finally, for each criterion the optimal model was determined.

Results Out of 629 patients, 585 (93%) patients received echocardiography and in 498 (79.2%) the LVEF could be calculated using Simpson´s biplane or monoplane method.

The BIC suggested two (panel B), the AIC three components (panel A). In the two-component model, mean ± SD LVEF values were 60.2 ± 8.7% and 30.8 ± 9.6%, thus covering 56% and 44% of patients, respectively (panel D). In the three-component model, respective LVEF values were 64.9 ± 6.2%, 50.2 ± 6.9%, and 28.4 ± 8.1%, thus covering 35%, 27%, and 38% of patients (panel C).

Conclusions Our analysis suggests that LVEF in patients with AHF is not a continuum, but clusters in two or three subgroups. In line with the HFrEF and HFpEF classification, the more conservative model suggested two subgroups of LVEF. The less restrictive model allowed for a third subgroup, compatible with HFmrEF. Future analyses will better characterize the identified subgroups.

Abstract P1432 Figure

P4380Echocardiographically determined myocardial work An emerging bioassay for clinical studies Results from the STAAB cohort study

Introduction

A novel echocardiographic method to non-invasively determine myocardial work based on speckle-tracking derived longitudinal strain and blood pressure has recently been validated and offers new opportunities to study the mechanistic associations. Heart failure patients with prolonged electrical conduction (ie, left bundle branch block) exhibit reduced myocardial global work efficiency (GWE) due to an increase in global wasted work (GWW), which could be improved by biventricular pacing. We here investigated the association of ETI and myocardial work in a non-diseased population.

Methods

The Characteristics and Course of Heart Failure STAges A/B and Determinants of Progression (STAAB) cohort study carefully characterized a representative sample of the population of a medium-sized town in Germany, aged 30–79 years and free from heart failure. Off-line analysis of the standardized, quality-controlled transthoracic echocardiograms regarding myocardial work yields the following parameters: global constructive work (GCW): work performed during shortening in systole and adding negative work during lengthening in isovolumic relaxation; global wasted work (GWW): negative work performed during lengthening in systole adding work performed during shortening in isovolumic relaxation; and global work efficiency (GWE): GCW/(GCW+GWW).

Results

We performed myocardial work analysis in 935 individuals from the sample of the first planned STAAB interim analysis who were in sinus rhythm, had preserved left ventricular ejection fraction and were free from significant valvular disease (51% female, 53±12 years). In linear regression including age, sex, heart rate, and ETI, we found increasing heart rate (64±10 bpm), QRS width (95±12 ms), QT interval (414±28 ms), and PQ interval (164±28 ms) associated with lower GWE (−0.11, −0.02, −0.03, and −0.001, respectively; all p<0.05) and higher GWW (+2.64, +0.29, +0.79, +0.16 mmHg%, respectively; all p<0.05).

Conclusion

In subjects free of overt cardiac disease, GWE strongly associated with ETI. Prolonged atrio-ventricular and intra-ventricular coupling and repolarization was associated with an increase in wasted work, while constructive work was not affected. These findings not only suggest a positive effect on myocardial energetics by reducing the heart rate, but also advocate the concept of myocardial work as a bioassay that is responsive to subtle changes. Myocardial work holds promise to be further studied in diseased patient groups.

Acknowledgement/Funding

German Ministry of Research and Education within the Comprehensive Heart Failure Centre Würzburg (BMBF 01EO1004 and 01EO1504)

4305The interrelation of left ventricular geometry with myocardial work

Introduction

A novel echocardiographic method to non-invasively determine myocardial work based on speckle-tracking derived longitudinal strain and blood pressure has recently been validated and offers new opportunities to study mechanistic associations. Left ventricular (LV) dilation and LV hypertrophy are acknowledged precursors of myocardial dysfunction and ultimately heart failure, but the mechanisms are still not well understood. We aimed to assess the association of LV geometry and myocardial work in a non-diseased population.

Methods

The Characteristics and Course of Heart Failure STAges A/B and Determinants of Progression (STAAB) cohort study carefully characterized a representative sample of the population of a medium-sized town in Germany, aged 30–79 years. By off-line analysis of the standardized, quality-controlled transthoracic echocardiograms the following parameters describing myocardial work can be derived. Global constructive work (GCW): work performed during shortening in systole and adding negative work during lengthening in isovolumic relaxation; global wasted work (GWW): negative work performed during lengthening in systole adding work performed during shortening in isovolumic relaxation; global work efficiency (GWE): GCW/(GCW+GWW). Further, LV volumes and mass were measured and indexed to body surface area.

Results

Myocardial work analysis was performed in 1568 individuals, who were in sinus rhythm, had preserved LV ejection fraction (EF), and were free from significant valvular disease (50.3% female, aged 53±12 years). In linear regression, we included age, sex, LVEF, low-density lipoprotein (LDL), glycosylated hemoglobin (HbA1c), heart rate, body mass index, hypertension as well as LV mass index (LVMi) and LV end-diastolic volume index (LVEDVi) as parameters of LV geometry. We found increasing LVEDVi (52±10 mL/m2), associated with higher GWW (+0.35, p<0.001) and lower GWE (–0.01, p<0.05), while increasing LVMi (73±17 g/m2) was associated with both, higher GWW (+0.23, p<0.01) and GCW (+1.6, p<0.05) resulting in a lower GWE (–0.09, p<0.01).

Conclusion

The new echocardiography-based method to non-invasively assess myocardial work offers new insights into the relationship of LV geometry and myocardial work in a non-diseased population. While larger LV volumes were associated with more wasted work, higher LV mass was associated with an increase in both constructive and wasted work. Both alterations of LV geometry adversely affected myocardial work efficiency. This new echocardiographic method is change-sensitive and thus holds promise to further explore the relationship of LV geometry with myocardial work in different disease entities.

Acknowledgement/Funding

Funding of the STAAB cohort study in the frame of the Comprehensive Heart Failure Center, BMBF 01EO1004 and 01EO1504

Glucose metabolism after pancreas transplantation

After pancreas transplantation in type-I diabetics the dependency on exogenous insulin usually vanishes rapidly. In about 50% of patients fasting and postprandial blood glucose concentrations are normal but by oral glucose tolerance tests the glucose metabolism is classified as normal in a minority. Some of the reasons for failure in obtaining good metabolic control are discussed. Attention is focused on the inevitable peripheral hyperinsulinemia and concomitant portal hypoinsulinemia related to the extra-portal administration of insulin.

Relationship between turnover rate and oxidation rate of alanine in the post-absorptive state and during parenteral nutrition before and after surgery

The influence of total parenteral nutrition and stomach resection on alanine turnover rate and alanine oxidation rate was measured in ten patients after single injection of U-14 C-alanine. Sequential studies were done in three patients. During parenteral nutrition alanine turnover was significantly higher than in the post-abortive state (14.75 +/- 2.56 mumol kg-1 min-1 and 8.48 +/- 1.88 mumol kg-1 min-1, respectively; P less than 0.01, mean +/- s.d.). Surgery had no additional significant influence on alanine turnover. In the post-absorptive state 4.71 +/- 0.71 mumol kg-1 min-1 was oxidized, during parenteral feeding before surgery 7.93 +/- 1.93 mumol kg-1 min-1 (P less than 0.01 v. post-absorptive state), and during parenteral feeding after surgery 7.67 +/- 1.67 mumol kg-1 min-1. The percentages of alanine turnover used for oxidation in the post-absorptive state and during parenteral feeding before and after surgery were 57 +/- 11%, 54 +/- 7% and 45 +/- 11%, respectively (no significant differences). It is concluded that the degree of alanine oxidation seems to be directed by the degree of alanine turnover. A discussion about differences in alanine oxidation under different circumstances must therefore include a discussion about changes in alanine turnover.

The relationship between gluconeogenesis from alanine and insulin, glucagon, cortisol and catecholamines after stomach resection

A hormonal influence on gluconeogenesis after stomach resection was sought by correlating the degree of carbon flux from alanine to glucose with the plasma levels of insulin, glucagon, adrenaline, noradrenaline and cortisol and with the urinary excretion of catecholamines, (nor)metanephrines and cortisol. No correlation was found, suggesting that none of these hormones has a dominant influence on gluconeogenesis after stomach resection.

Gluconeogenesis and nitrogen loss after stomach resection

The relationship between gluconeogenesis from alanine and nitrogen balance after stomach resection was investigated in 13 patients. Partial stomach resection was done in eight patients and total stomach resection was done in five patients. Alanine turnover, carbon flux from alanine to glucose, and glucose turnover were determined by tracer methodology, using the single injection of [U-14C]alanine and [2-3H]glucose. The patients were divided in two groups according to the quantity of administered glucose. Six patients with partial stomach resection received 2.1 to 2.8 g glucose . kg-1 . day-1 and 0.07 to 0.09 g nitrogen . kg-1 . day-1, amounting to 11 to 13 kcal . kg-1 . day-1 (group 1). In group 2 the subjects received 5.4 to 8.2 g glucose . kg-1 . day-1 and 0.12 to 0.26 g nitrogen . kg-1 . day-1; five patients received also 1.2 to 1.8 g fat emulsion . kg-1 . day-1. Total caloric supply was 28 to 60 kcal . kg-1 . day-1. In group 1 the mean potential contribution of gluconeogenesis from alanine to nitrogen loss was between 31 and 67%; in group 2 this contribution was at least 7 to 63%. No correlation was found between nitrogen balance and carbon flux from alanine to glucose. A significant correlation (p less than 0.001) was found between nitrogen balance and, respectively, nitrogen intake and caloric supply. These results suggest that not gluconeogenesis from alanine but nitrogen and caloric demand are major factors influencing nitrogen balance after stomach resection.

Endogenous glucose production after stomach resection

Endogenous glucose production was measured in eight patients after stomach resection to determine glucose requirement after elective surgery in five patients during infusion of 2.1 - 2.9 g glucose.kg/day (low glucose) and in three patients during infusion of 6.2 - 6.9 g glucose.kg/day (high glucose). Endogenous glucose production was defined as the difference between total glucose turnover measured by 2-3H-glucose and the glucose infusion rate. Endogenous glucose production was the same in both groups, respectively 0.010 +/- 0.002 and 0.009 +/- 0.002 mmol kg/min. It was concluded that a daily quantity of glucose equal to the endogenous production of 180 g. 70 kg/day should be the minimum given after stomach resection.

Alanine turnover in the postabsorptive state and during parenteral hyperalimentation before and after surgery

Influence of total parenteral nutrition and operation on alanine turnover and venous alanine concentration was determined in 5 patients with stomach carcinoma using single technique of U-14C alanine. Every patient served at his own control. In the postabsorptive state alanine turnover was 1.63 +/- 0.31 mgatC . min-1, not different from a control group (1.84 +/- 0.60 mgatC . min-1); during total parenteral nutrition alanine turnover increased to 3.21 +/- 0.5g mgatC . min-1 with a rise in alanine concentration from 0.96 +/- 0.17 mgatC . L-1 + 0.69 +/- 0.22 mgatC . L-1. After surgery during the same total parenteral nutrition alanine turnover increased further to 3.78 +/- 0.17 mgatC . min-1 with a lowering of alanine concentration to 1.44 +/- 0.22 mgatC . L-1. The present results show the distinct influence of TPH on alanine kinetics. The present data indicate that alanine turnover cannot be deduced from blood alanine concentration.

Paradoxical diuresis after vasopressin administration to patients with neurohypophyseal diabetes insipidus treated with chlorpropamide, carbamazepine or clofibrate

1. Chlorpropamide, carbamazepine and clofibrate have an antidiuretic action in patients with neurohypophyseal diabetes insipidus which is qualitatively similar to that of antidiuretic hormone (ADH). 2. An additive antidiuretic effect is produced by combination of chlorpropamide and carbamazepine with small dosages of ADH. 3. After an immediate and transient antidiuresis, a single intravenous bolus injection of lysine vasopressin given during treatment with chlorpropamide, chlorpropamide with a continuous intravenous infusion of lysine vasopressin, carbamazepine or clofibrate, resulted in increased water diuresis for 12-24 h or longer. 4. This paradoxical diuresis was not observed during treatment with chlorothiazide. 5. It is suggested that the antidiuretic action of chlorpropamide, carbamazepine and clofibrate is localized at the receptor site for ADH in the distal renal tubular cell.

The antidiuretic action of carbamazepine in man

1. Carbamazepine had an antidiuretic effect in six patients with neurohypophyseal diabetes insipidus due to various causes. The effect was qualitatively similar to that of antidiuretic hormone.

2. At the time of maximal antidiuresis plasma arginine vasopressin levels, measured by radioimmunoassay, were below the limit of detectability in all patients.

3. In one of two control subjects a temporary decrease in water excretion was observed during administration or carbamazepine.

4. In the two control subjects plasma arginine vasopressin levels dropped from normal to below the level of detectability during administration of the drug.

5. It is concluded that the antidiuretic effect of carbamazepine is not the result of releasing endogenous antidiuretic hormone or of prolonging its half-life.

6. The most likely explanation for the observed results is either a direct effect of carbamazepine on the distal renal tubular cell or an increase of renal responsiveness to endogenous antidiuretic hormone.