Elevated plasma glucagon levels in cirrhosis of the liver

Unraveling the mechanisms of hepatogenous diabetes and its therapeutic perspectives

The review focused mainly on the pathogenesis of hepatogenous diabetes (HD) in liver cirrhosis (LC). This review reveals parallels between the mechanisms of metabolic dysfunction observed in LC and type II diabetes (T2DM), suggesting a shared pathway leading to HD. It underscores the role of insulin in HD pathogenesis, highlighting key factors such as insulin signaling, glucose metabolism, insulin resistance (IR), and the influence of adipocytes. Furthermore, the impact of adipose tissue accumulation, fatty acid metabolism, and pro-inflammatory cytokines like Tumor necrosis factor-α (TNF-α) on IR are discussed in the context of HD. Altered signaling pathways, disruptions in the endocrine system, liver inflammation, changes in muscle mass and composition, and modifications to the gut microbiota collectively contribute to the complex interplay linking cirrhosis and HD. This study highlights how important it is to identify and treat this complex condition in cirrhotic patients by thoroughly analyzing the link between cirrhosis, IR, and HD. It also emphasizes the vitality of targeted interventions. Cellular and molecular investigations into IR have revealed potential therapeutic targets for managing and preventing HD.

The Liver-α-Cell Axis in Health and in Disease

Glucagon and insulin are the main regulators of blood glucose. While the actions of insulin are extensively mapped, less is known about glucagon. Besides glucagon's role in glucose homeostasis, there are additional links between the pancreatic α-cells and the hepatocytes, often collectively referred to as the liver-α-cell axis, that may be of importance for health and disease. Thus, glucagon receptor antagonism (pharmacological or genetic), which disrupts the liver-α-cell axis, results not only in lower fasting glucose but also in reduced amino acid turnover and dyslipidemia. Here, we review the actions of glucagon on glucose homeostasis, amino acid catabolism, and lipid metabolism in the context of the liver-α-cell axis. The concept of glucagon resistance is also discussed, and we argue that the various elements of the liver-α-cell axis may be differentially affected in metabolic diseases such as diabetes, obesity, and nonalcoholic fatty liver disease (NAFLD). This conceptual rethinking of glucagon biology may explain why patients with type 2 diabetes have hyperglucagonemia and how NAFLD disrupts the liver-α-cell axis, compromising the normal glucagon-mediated enhancement of substrate-induced amino acid turnover and possibly fatty acid β-oxidation. In contrast to amino acid catabolism, glucagon-induced glucose production may not be affected by NAFLD, explaining the diabetogenic effect of NAFLD-associated hyperglucagonemia. Consideration of the liver-α-cell axis is essential to understanding the complex pathophysiology underlying diabetes and other metabolic diseases.

Non-alcoholic fatty liver disease alters expression of genes governing hepatic nitrogen conversion

BACKGROUND & AIMS

We recently showed that the functional capacity for ureagenesis is deficient in non-alcoholic fatty liver disease (NAFLD) patients. The aim of this study was to assess expression of urea cycle-related genes to elucidate a possible gene regulatory basis to the functional problem.

METHODS

Liver mRNA expression analyses within the gene pathway governing hepatic nitrogen conversion were performed in 20 non-diabetic, biopsy-proven NAFLD patients (8 simple steatosis; 12 non-alcoholic steatohepatitis [NASH]) and 12 obese and 14 lean healthy individuals. Sixteen NAFLD patients were included for gene expression validation. Relationship between gene expressions and functional capacity for ureagenesis was described.

RESULTS

Gene expression of most urea cycle-related enzymes were downregulated in NAFLD vs both control groups; markedly so for the urea cycle flux-generating carbamoyl phosphate synthetase (CPS1) (~3.5-fold, P < .0001). In NASH, CPS1 downregulation paralleled the deficit in ureagenesis (P = .03). Additionally, expression of several genes involved in amino acid uptake and degradation, and the glucagon receptor gene, were downregulated in NAFLD. Conversely, glutamine synthetase (GS) expression increased >1.5-fold (P ≤ .03), inversely related to CPS1 expression (P = .004).

CONCLUSIONS

NAFLD downregulated the expression of urea cycle-related genes. Downregulation of urea cycle flux-generating CPS1 correlated with the loss of functional capacity for ureagenesis in NASH. On gene level, these changes coincided with an increase in the major ammonia scavenging enzyme GS. The effects seemed related to a fatty liver as such rather than NASH or obesity. The findings support gene regulatory mechanisms involved in the deficient ureagenesis of NAFLD, but it remains unexplained how hepatocyte fat accumulation exerts these effects.

Decreased expression of insulin and increased expression of pancreatic transcription factor PDX-1 in islets in patients with liver cirrhosis: a comparative investigation using human autopsy specimens

BACKGROUND

Glucose intolerance in patients with liver cirrhosis (LC), known as hepatogenous diabetes, is thought to be distinct from type 2 diabetes (T2DM) in some aspects. Hyperinsulinemia and/or insulin resistance in liver disease is associated with hepatocarcinogenesis, growth of hepatocellular carcinoma, and poor prognosis. However, the pathophysiological processes in islets that are responsible for hyperinsulinemia in LC are still not precisely known. Therefore, we investigated the histopathological differences in islets of Langerhans cells between LC and T2DM.

METHODS

A total of 35 human autopsy pancreatic tissue samples were used in this study (control, n = 18; T2DM, n = 6; LC, n = 11). The expression of insulin, glucagon, somatostatin, pancreatic duodenal homeobox-1 (PDX-1), proliferating cell nuclear antigen (PCNA), and Ki-67 was examined using immunohistochemistry and quantitated by image analysis.

RESULTS

Islet hypertrophy and a significant increase in PCNA-positive cells in islets were observed in the tissues from LC cases. The insulin-positive areas in islets were significantly decreased in LC cases compared with control and T2DM cases (P = 0.001, P = 0.035, respectively), whereas the PDX-1-positive area was significantly increased in LC cases (P = 0.001) compared with the control. Furthermore, disorganization of pancreatic endocrine cells and nucleocytoplasmic translocation of PDX-1 were both seen in the LC subjects.

CONCLUSIONS

In LC, islets undergo hypertrophy and exhibit paradoxical expression of insulin and PDX-1. In the subjects autopsied, insulin expression was decreased, whereas expression of the pancreatic transcription factor PDX-1 was increased in LC. These results point to important distinctions between LC and T2DM.

Signals for glucagon secretion

The normal physiological role of glucagon is in controlling hepatic glucose output. Glucagon subserves the role of homeostasis by maintaining plasma glucose and of a stress hormone by producing hyperglycaemia. While control of glucagon release by circulating metabolites and also other hormones is clearly important, it seems likely that the nervous system exerts an over-riding influence. The parasympathetic nervous system maintains homeostasis and the sympathetic acts in stress. Glucagon levels are found to be high in cirrhosis and also after acute hepatic failure. It is likely that these changes in glucagon concentration are secondary to metabolic abnormalities. While some glucagon is cleared by the liver, a similar clearance is seen by many other tissues and it is not likely that the elevation of glucagon seen in liver failure is due solely to a gross deficiency of glucagon clearance. No liver abnormality is seen in the glucagonoma syndrome, where glucagon concentration are chronically high, or in patients who have had a total pancreatectomy, where plasma glucagon is undetectably low. It thus seems unlikely that liver mass is importantly controlled by glucagon.

Dextrose in the banked blood products does not seem to affect the blood glucose levels in patients undergoing liver transplantation

AIM

Hyperglycemia commonly seen in liver transplantation (LT) has often been attributed to the dextrose in the storage solution of blood transfusion products. The purpose of the study is to compare the changes of the blood glucose levels in transfused and non-transfused patients during LT.

METHODS

A retrospective study on 60 biliary pediatric patients and 16 adult patients undergoing LT was carried out. Transfused pediatric patients were included in Group I (GI), those not transfused in Group II (GII). Twelve adult patients were not given transfusion and assigned to Group III (GIII); whereas, four adult patients who received massive transfusion were assigned to Group IV (GIV). The blood glucose levels, volume of blood transfused, and the volume of crystalloid infused were recorded, compared and analyzed.

RESULTS

Results showed that the changes in blood glucose levels during LT for both non-transfused and minimally transfused pediatric groups and non-transfused and massively-transfused adult groups were almost the same.

CONCLUSION

We conclude that blood transfusion does not cause significant changes in the blood glucose levels in this study.

Inhibition of glucagon improves splanchnic hyporesponse to terlipressin in cirrhotic rats with blood retention in the gastric lumen

BACKGROUND/AIMS

Portal hypotensive effect of terlipressin is less effective when given during hemorrhage than in stable state. Blood retention in the stomach can induce splanchnic hyperemia which is mainly a consequence of an increased glucagon release. This study was undertaken to evaluate whether gastric blood retention contributes to the splanchnic hyporesponse to terlipressin.

METHODS

Plasma glucagon determination was performed under basal conditions and after intragastric blood gavage in sham-operated and cirrhotic rats. Additionally, splanchnic hemodynamic effects to terlipressin were measured in blood-gavaged cirrhotic rats with or without glucagon antiserum or octreotide infusion. Another set of air-gavaged cirrhotic rats was included for comparison.

RESULTS

Plasma glucagon level increased in both sham-operated and cirrhotic rats following blood gavage. Compared to air-gavaged cirrhotic rats, splanchnic hyporesponse to terlipressin was observed in cirrhotic rats receiving intragastric blood gavage. However, this splanchnic hyporesponse to terlipressin in blood-gavaged cirrhotic rats was overcome by glucagon antiserum or octreotide infusion.

CONCLUSIONS

Intragastric blood gavage induced an elevation of plasma glucagon level and led to a splanchnic hyporesponse to terlipressin. Glucagon antiserum or octreotide administration overcame this hyporesponse. Excessive release of circulating glucagon may be an important factor for splanchnic hyporesponse to terlipressin in cirrhotic portal hypertension during hemorrhage.

Intestinal glutaminase activity is increased in liver cirrhosis and correlates with minimal hepatic encephalopathy

BACKGROUND/AIMS

We performed the current study to assess the intestinal activity of enterocyte phosphate-activated glutaminase (PAG) in cirrhosis.

METHODS

Forty-nine cirrhotic patients and 36 control subjects underwent endoscopic duodenal biopsies. Minimal hepatic encephalopathy (MHE) was evaluated using three psychometric tests. Oral glutamine challenge (OGC) was performed and MELD, Child-Pugh and the presence of esophageal varices were recorded. PAG was measured by enzymatic methods. Cerebral magnetic resonance spectroscopy was performed in 10 cirrhotics.

RESULTS

PAG was found to be higher in cirrhotics than control subjects 2.4+/-1.51 vs. 0.68+/-0.57IU/mg protein (P<0.001). PAG was also increased in patients with MHE and correlated with MELD, INR, esophageal varices and serum bile acids. A negative correlation was observed between PAG activity and intra-cerebral choline/creatine ratio (r=-0.67; P=0.035) and a positive correlation with glutamine plus glutamate/creatine ratio (r=0.78; P=0.007). In multivariate analysis using backward logistic regression, presence of MHE was the only variable independently related to altered enterocyte PAG.

CONCLUSIONS

Enterocyte PAG is increased in cirrhotic patients and correlates with MHE. These data support a possible role for intestinal glutaminase in the pathogenesis of hepatic encephalopathy (HE) and could be a new target for future therapies.

Alterations in thyroid Doppler arterial resistance indices, volume and hormones in cirrhosis: relationships with splanchnic haemodynamics

The hypothesis of thyroid involvement in the haemodynamic alterations of cirrhosis was evaluated. We measured thyroid volume (thrV), free triiodiothyronine (FT3), free thyroxin (FT4), thyroid stimulating hormone (TSH), resistance index (thrRI) and pulsatility index (thrPI) in the inferior thyroid artery in 45 cirrhotic patients of different aetiologies and Child class, and in 13 healthy subjects. Portal vein velocity, flow, diameter and hepatic, splenic, and renal arterial resistance indices were also evaluated. ThrV was increased in Child-C patients (p < 0.05). FT3 was decreased in cirrhotic patients (p < 0.05), TSH and FT4 were not different. ThrPI and thrRI were increased in cirrhotic patients (thrPI: 1.01 +/- 0.15 vs. 0.81 +/- 0.11; thrRI: 0.62 +/- 0.05 vs. 0.53 +/- 0.04; p < 0.01) and were inversely correlated with FT3 (p < 0.05), and directly correlated with hepatic, splenic and renal resistance indices (p < 0.01). In conclusion, thyroid is involved, primarily and secondarily, in the haemodynamic alterations of cirrhosis; a reduction in vasodilator FT3 may play a role in the pathophysiology.

The contribution of afferent signals from the liver to metabolic regulation during exercise

The crucial role of the liver as the only organ to produce glucose used by skeletal muscle during exercise is well known. Since hepatic glucose production is central to blood glucose homeostasis during exercise, it has been postulated that the liver may inform the central nervous system and other organs of its diminishing capacity to produce glucose from glycogen, before blood glucose falls. The sensory role of the liver during exercise would be similar to its role in the control of food intake. As a consequence, the experimental approaches used to test the hypothesis that afferent signals from the liver contribute to metabolic regulation during exercise are inspired by those used to test the same hypothesis in the regulation of food intake. In the present review, two questions are addressed. The existing evidence for the liver's sensory influence on metabolic adjustments to exercise is first reviewed; the nature of the initiating stimuli for the afferent contribution of the liver to physical exercise is discussed thereafter. The hypothetical construct upon which rests the contribution of the liver's afferent signals to metabolic regulation during exercise is that a decrease in liver glycogen or a related metabolic intermediate is sensed by the liver, and the signal is transduced to the central nervous system, most likely through the afferent activity of the hepatic vagus nerve, where it contributes to the orchestration of the metabolic and hormonal responses to exercise. Support in favour of this construct comes mainly from the demonstration that sectioning of the hepatic vagus nerve attenuates the normal hormonal response to exercise. It seems that the liver-glucagon axis is particularly responsive to this reflex activation. In other respects, the hepatic mechanism responsible for linking the metabolic activity in the liver to an afferent signal capable of regulating the metabolic response to exercise remains speculative. Substrates or derivatives of substrate oxidation, energy-related compounds (ATP and Pi), or changes in cell volume may all be related to changes in transmembrane potential in the liver cell, which according to the "potentiostatic" theory would determine the afferent vagal activity.

Hypokalaemia in alcoholic patients

Hypokalaemia is commonly found among the electrolyte abnormalities observed in chronic alcoholics. However, the underlying mechanisms of the decreased potassium levels are not well known. We undertook the present study to analyse the possible pathogenetic mechanisms of hypokalaemia in a large group of alcoholic patients (n = 127) admitted to our hospital for causes related to alcohol abuse. Serum potassium levels were significantly lower in alcoholic patients compared to the control population (3.8 + 1.1 mmol/l vs. 4.6 + 0.9 mmol/l). In 12 of these patients inappropriate kaliuresis was observed due mainly to the coexistent hypomagnesaemia. Two of the remaining four patients had a history of diarrhoea, while the other two had alcohol withdrawal syndrome with considerable respiratory alkalosis. Patients with hypokalaemia had hypomagnesaemia and respiratory alkalosis more commonly compared to the normokalaemic ones. We conclude that hypokalaemia is a relatively common electrolyte abnormality observed in alcoholic patients owing to various pathophysiological mechanisms. Among them, inappropriate kaliuresis due to the co-existent hypomagnesaemia predominates.

The effects of endoscopic variceal ligation and propranolol on portal hypertensive gastropathy: a prospective, controlled trial

BACKGROUND

Endoscopic treatment of esophageal varices may accentuate portal hypertensive gastropathy. The impact of the combination of band ligation and propranolol on this condition remains unknown.

METHODS

Patients with history of variceal bleeding were randomized to receive band ligation alone (control group, 40 patients) or a combination of band ligation and propranolol (propranolol group, 37 patients). Serial endoscopic evaluation of gastropathy was performed. Gastropathy was classified into 3 grades and scored as 0, 1, or 2.

RESULTS

Before endoscopic treatment, 17% of the control group and 22% of the propranolol group had gastropathy (p = 0.78). The occurrence of gastropathy after endoscopic treatment was significantly higher in the control group than in the propranolol group (p = 0.002). Serial endoscopic follow-up revealed that the mean gastropathy score was significantly higher in the control group than in the propranolol group (p < 0.05). In patients with gastropathy the gastropathy score reached a peak at 6 months after endoscopic treatment in both the control and propranolol groups (85% vs. 48%, respectively). After variceal obliteration, accentuation of gastropathy was significant in the control group (p < 0.01) but not in the propranolol group. Gastropathy was less likely to develop in patients who developed gastric varices. Esophageal variceal recurrence was not related to the development of gastropathy after variceal obliteration with banding. Only one patient in the control group bled from gastropathy.

CONCLUSION

Band ligation of esophageal varices may accentuate gastropathy, which in this study was partly relieved by propranolol.

Vascular smooth muscle cell signaling in cirrhosis and portal hypertension

Abnormal vascular responsiveness to ligands has been frequently observed in cirrhosis and portal hypertension, but its existence is not proven. The signaling pathways in vascular smooth muscle cells (VSMCs) have been studied only in animal models of cirrhosis and portal hypertension. Emerging evidence suggests that active relaxation, expressed as augmented content or activity of effectors within the cyclic AMP signaling pathway and suppressed content or activity of effectors in the inositol 1,4,5-trisphosphate/1,2-diacylglycerol signaling pathway, may be occurring in VSMCs of the splanchnic circulation in portal hypertension. The evidence supporting the existence of this phenomenon in the VSMCs of extrasplanchnic circulations in portal hypertension, as well as in the splanchnic circulation when chronic cellular damage is present, is very limited. The status of the other signaling pathways associated with contractile functions of the VSMCs, viz., cyclic GMP and tyrosine kinase-linked pathways, is unknown. The status of all the signaling pathways in non-contractile functions of VSMCs, such as growth and remodeling, has not been studied. As our overall understanding on the signaling pathways in VSMCs is only emerging, it is premature to implicate altered activity of the signaling pathways as the underlying basis of vascular hyporesponsiveness in cirrhosis and portal hypertension, and to extrapolate these limited observations to the human condition.

The hepatopulmonary syndrome

The hepatopulmonary syndrome is a triad of liver disease, increased alveolar-arterial oxygen gradient and intrapulmonary vascular dilatations. Manifestations include orthodeoxia, platypnoea and hyperdynamic circulation. Intrapulmonary vascular abnormalities, perhaps mediated by nitric oxide, cause hypoxaemia by shunting, a perfusion-diffusion defect, and ventilation-perfusion mismatching. Contrast-enhanced echocardiography is the method of choice for demonstrating pulmonary vascular abnormalities, although perfusion lung scanning is a more specific and sensitive test. Angiography is best reserved for patients with poor response to 100% oxygen and defines whether vascular dilatations are of the diffuse 'spongy' type or, less commonly, discrete arteriovenous communications amenable to embolization. About 80% of patients with the hepatopulmonary syndrome eventually have improved oxygenation after liver transplantation, thereby making worsening hypoxaemia the primary indication for transplantation in many instances. Nevertheless, severe hypoxaemia carries a peri-operative mortality of 30% and reliable predictors of successful outcome after transplantation remain to be determined.

Cardiovascular effects of alcohol

The ingestion of one or two alcoholic drinks can affect heart rate, blood pressure, cardiac output, myocardial contractility, and regional blood flow. These actions generally are not clinically important. In the presence of cardiovascular disease, however, even such small quantities of alcohol might result in transient unfavorable hemodynamic changes. Moreover, alcohol abuse can produce cardiac arrhythmias, hypertension, cardiomyopathy, stroke, and even sudden death. In contrast, moderate alcohol use produces changes that have an overall favorable effect on atherosclerotic-related vascular diseases. Because cardiovascular disease due to atherosclerosis is the leading cause of death in Western society, this desirable effect of alcohol use outweighs its detrimental actions, resulting in favorable findings in population studies. Nevertheless, the body of evidence argues against encouraging alcohol use for its cardiovascular effects.

Portal-hypertensive gastropathy

In the present article we describe updated information concerning the clinical feature of portal-hypertensive gastropathy (PHG), which is characterized by mucosal and submucosal vascular dilatation without inflammation. Although this lesion represents non-variceal bleeding, there is a wide variation of its prevalence. Portal pressure and some humoral factors may play important roles in its pathogenesis. Gastric acid secretory activity is reduced, whereas the gastric mucosal barrier is impaired. With regard to gastric mucosal haemodynamics, whether 'overflow' (i.e. active congestion) or 'stasis' (i.e. passive congestion) cause gastric mucosal hyperaemia is not known. A severe lesion is a potential source of bleeding, while mild lesions are of little clinical significance and endoscopic variceal obliteration aggravates PHG in some patients. In the treatment of PHG, pharmacological (e.g. propranolol), surgical (e.g. portosystemic shunt) and radiological (e.g. transjugular intrahepatic portosystemic shunt) procedures may be useful in preventing bleeding from PHG.

Insulin secretory capacity and the regulation of glucagon secretion in diabetic and non-diabetic alcoholic cirrhotic patients

BACKGROUND/AIMS

Insulin secretion is increased in cirrhotic patients without diabetes but decreased in cirrhotic patients with diabetes. Increased glucagon secretion is found in both groups. Our aim was to determine: 1) whether alterations in insulin secretion are due to changes in maximal secretory capacity or altered islet B-cell sensitivity to glucose, and 2) whether regulation of glucagon secretion by glucose is disturbed.

METHODS

Insulin, C-peptide and glucagon levels were measured basally and during 12, 19 and 28 mmol/l glucose clamps, and in response to 5 g intravenous arginine basally and after 35 min at a glucose of 12, 19 and 28 mmol/l in 6 non-diabetic alcoholic cirrhotic patients, six diabetic alcoholic cirrhotic patients and six normal controls.

RESULTS

Fasting insulin, and C-peptide levels were higher in cirrhotic patients than controls but not different between diabetic and non-diabetic patients. C-peptide levels at t=35 min of the clamp increased more with glucose concentration in non-diabetic cirrhotic patients than controls; there was little increase in diabetic cirrhotic patients. At a blood glucose of approximately 5 mmol/l the 2-5 min C-peptide response to arginine (CP[ARG]) was similar in all groups, but enhancement of this response by glucose was greater in non-diabetic cirrhotic patients and impaired in diabetic cirrhotic patients. Maximal insulin secretion (CP(ARG) at 28 mmol/l glucose) was 49% higher in the non-diabetic cirrhotic patients than controls (p<0.05); in diabetic cirrhotic patients it was 47% lower (p<0.05). The glucose level required for half-maximal potentiation of (CPARG) was not different in the three groups. Cirrhotic patients had higher fasting glucagon levels, and a greater 2-5-min glucagon response to arginine, which was enhanced by concomitant diabetes (p<0.001 vs controls). Suppression of plasma glucagon by hyperglycaemia was markedly impaired in diabetic cirrhotic patients (glucagon levels at 35 min of 28 mmol/l glucose clamp: diabetics, 139 x/divided by 1.25 ng/l, non-diabetic cirrhotic patients, 24 x/divided by 1.20, controls, 21 x/divided by 1.15, p<0.001). Suppression of arginine-stimulated glucagon secretion by glucose was also impaired in diabetic cirrhotic patients, and to a lesser extent in non-diabetic cirrhotic patients.

CONCLUSIONS

Insulin secretory abnormalities in diabetic and non-diabetic cirrhotic patients are due to changes in maximal secretory capacity rather than altered B-cell sensitivity to glucose. The exaggerated glucagon response to arginine in alcoholic cirrhotic patients is not abolished by hyperglycaemia/hyperinsulinaemia. In diabetic alcoholic cirrhotic patients, the inhibitory effect of glucose on basal glucagon secretion is also markedly impaired.

Effect of posture-induced blood volume expansion on systemic and regional hemodynamics in patients with cirrhosis

BACKGROUND/AIMS

This study aimed to investigate the effects of posture-induced blood volume expansion on systemic and regional hemodynamics in patients with cirrhosis.

METHODS

The mean arterial pressure, cardiac index, peripheral vascular resistance index, and flow volume index of the superior mesenteric artery (SMA) and femoral artery (FA) were measured in 10 patients with cirrhosis and portal hypertension and 10 controls after they had been standing for 2 h. Plasma atrial natriuretic peptide, plasma renin activity, and plasma glucagon levels were also determined. These measurements were repeated after 30 min and 60 min when the patients were recumbent.

RESULTS

In the upright posture, systemic hemodynamics, FA blood flow index, plasma atrial natriuretic peptide level, and plasma renin activity level were similar in patients and controls. However, SMA blood flow index and plasma glucagon level were significantly higher in patients than in controls. On the assumption of the supine position, cardiac index and plasma atrial natriuretic peptide level significantly increased in the two groups, but the changes were greater in patients than in controls. Mean arterial pressure remained unchanged. The reduction in peripheral vascular resistance index was therefore greater in patients in controls. SMA and FA blood flow index increased significantly in the two groups, but the changes were greater in patients than in controls. Furthermore, SMA blood flow fraction (SMA blood flow index/cardiac index) was steady in controls, whereas it increased significantly in patients. In contrast, FA blood flow fraction (FA blood flow index/cardiac index) remained unchanged in the two groups. In patients, the change in peripheral vascular resistance index was correlated inversely with that of SMA blood flow index, but not with that of FA blood flow index. Plasma renin activity level dropped significantly, but the decline was similar in the two groups. Plasma glucagon level was not modified in either group.

CONCLUSIONS

In patients with cirrhosis, splanchnic vasodilation appears to be present, even in the upright position, and further abnormal vasodilation occurs on recumbency-induced blood volume expansion. This abnormal shear-stress phenomenon observed in the splanchnic circulation seems to be mediated by a local vasodilator rather than a general vasodilator.

Effects of dietary manipulations and glucose infusion on glucagon response during exercise in rats

The purpose of the present investigation was to test the hypothesis that blood glucose concentration is not always related to glucagon response during exercise. Three groups of rats were submitted to a prolonged (3-h) swimming exercise. Two groups of rats had their normal food intake restricted by 50% the night before the experiment. One of these two groups of rats was intravenously infused with glucose throughout exercise to maintain euglycemia. The third group of rats swam while under normal dietary conditions. Plasma glucose, sampled in arterial blood, was reduced (P < 0.05) at 75, 105, 150, and 170 min of exercise (from approximately 130 to 110 mg/dl) in the food-restricted animals without glucose infusion, whereas a significant (P < 0.05) increase was measured in the two other groups during exercise. A significant (P < 0.01) difference in the mean integrated areas under the glucose-concentration curve was found only between the fed and the two food-restricted groups. Plasma insulin concentrations decreased (P < 0.05) similarly in all groups during exercise, whereas plasma epinephrine and norepinephrine concentrations increased significantly (P < 0.01) in all groups. Despite differences between groups in plasma glucose response during exercise, and despite the absence of any decrease in exercising blood glucose levels in at least two of the three groups, plasma glucagon responses were increased (P < 0.05) similarly in all groups (from approximately 250 to 550 pg/ml) at the end of the exercise period. The increase in glucagon was significant after 90 min of exercise in the food-restricted groups, with or without glucose infusion, but only after 140 min in the fed group. These results indicate that the glucagon response during exercise is not always linked to the decrease in plasma glucose.

New aspects on etiology, biochemistry, and therapy of portal systemic encephalopathy: a critical survey

There is scientific agreement that portal systemic encephalopathy (PSE) is caused morphologically by portal systemic shunts and biochemically by constituents of the portal venous blood. Ammonium has a key role in the pathogenesis of PSE. Direct correlations with the degree of PSE have been established exclusively with glutamine, i.e. the terminal product of the peripheral detoxification of ammonium. In PSE, ammonium is probably responsible for damage to astrocytic and neuronal cells. Ammonium's toxic effect is due to the intracerebral glutamine synthesis. After several metabolic steps, which will be discussed in detail, brain cell damage is caused directly or indirectly (exitotoxically) by energy deficiency. Hyperammonemia and PSE are each well defined though different forms of disturbance. Therefore, ammonium is not the sole decisive factor in the pathogenesis of PSE. We performed a detailed and critical analysis of all studies on amino acid therapy of PSE, especially those that were randomized and controlled. This analysis revealed a close and direct correlation between qualitative and quantitative dosages of amino acids on one hand, and parallel improvements of amino acid imbalance (essentially associated with PSE) and degree of PSE on the other. A close and direct dose/efficacy correlation must be assumed. Disturbed plasmatic amino acid homeostasis and cerebral monoaminergic neurotransmission are probably important pathogenic factors of PSE. A fundamental cofactor in the efficacy of each adequate amino acid therapy might be a substantial decrease of endogenous ammonium production. Physiologic benzodiazepines may also have an important function in the pathogenesis of PSE: not so, however, the glutamate-ergic and GABA-ergic neurotransmission, which are disturbed principally in PSE. In close correlation to pathogenesis, established and proposed therapies of PSE are critically discussed.

Hyperglucagonaemia in cirrhotic patients and its relationship to the severity of cirrhosis and haemodynamic values

Plasma glucagon concentrations were measured in 160 cirrhotic patients (Pugh's grade A in 52 patients, Pugh's grade B in 64 patients and Pugh's grade C in 44 patients). These values were compared with plasma glucagon concentrations in 57 age and sex-matched healthy subjects. Systemic and portal haemodynamic measurements, effective renal plasma flow and creatinine clearance were recorded for each patient. Plasma glucagon levels were significantly increased in cirrhotic patients compared with healthy subjects. In addition, plasma glucagon levels were higher in cirrhotic patients with ascites than in those without ascites and were increased in relation to the severity of cirrhosis as assessed by Pugh's score. Multiple linear regression found that only Child-Pugh's score was estimated to be an independent predictor of hyperglucagonaemia in cirrhotic patients. However, in patients with different degrees of oesophageal varices and in patients without oesophageal varices, plasma glucagon concentrations were no different among the different groups of patients, but were still higher than plasma glucagon concentrations in healthy subjects. In contrast, plasma glucagon levels were negatively correlated with mean arterial pressure and systemic vascular resistance. The results of the present study suggest that impairment of liver function plays, in part, a role in increased plasma glucagon levels observed in patients with cirrhosis. In addition, these data support the hypothesis that hyperglucagonaemia may contribute, at least in part, to the pathogenesis of peripheral arterial vasodilatation in cirrhosis with portal hypertension.

Hepatopulmonary syndrome. A pulmonary vascular complication of liver disease

Hepatopulmonary syndrome is part of the spectrum of pulmonary vascular disorders seen in advanced liver disease. The pathophysiology of these entities likely is dependent on the degree of pulmonary vasoconstriction or vasodilation that occurs. Our understanding of hepatopulmonary syndrome has helped further our knowledge of the interaction of the liver and the lung. Advances in the management of this disorder, especially liver transplantation, finally have allowed us to offer some hope to patients with this disease.

Mediators, cytokines, and growth factors in liver-lung interactions

Multiple mediators have been implicated in the interactions between the liver and the lungs in various disease states. The best characterized mediator of liver-lung interaction is alpha 1-antitrypsin. Several cytokines and mediators may be involved in the pathogenesis of the hepatopulmonary syndrome and in the cytokine cascades that are activated in systemic inflammatory states such as acute respiratory distress syndrome. Hepatocyte growth factor or scatter factor is a recently described peptide with a broad range of biologic effects that may mediate lung-liver interactions.

Glucagon, stress, and portal hypertension. Plasma glucagon levels and portal hypertension in relation to anesthesia and surgical stress

Glucagon has been proposed as the mediator of splanchnic hyperemia in portal hypertension. Employing an assay specific for pancreatic glucagon, we reevaluated the relationship between this peptide and portal hypertension in the portal vein (PV)-stenosed rat model addressing, in particular, the effects of anesthesia and surgical stress. Plasma glucagon levels were similar in sham-operated and portal hypertensive rats: glucagon, sham vs PV stenosed: 110.7 +/- 17.1 pmol/liter vs 140.6 +/- 23.3 pmol/liter (NS). Furthermore, plasma levels of glucagon and the related peptide VIP were not significantly influenced by anesthesia or surgical stress, and levels remained similar under all conditions in sham-operated and PV-stenosed animals. We conclude that pancreatic glucagon is not elevated in the PV-stenosed rat; differences between these results and those describing hyperglucagonemia in this model cannot be explained on the basis of a differential response to stress but may reflect differences in glucagon assay system.

Insulin and glucagon levels in living related liver transplantation: their interaction with the recovery of graft liver function

Insulin and glucagon have opposite effects on various hepatic functions, including energy metabolism, which is essential for hepatic viability. To evaluate the effects of insulin and glucagon on the recovery of graft liver function, changes in these levels were investigated in relation to arterial ketone body ration (AKBR) during a 30-h period after graft liver reperfusion in 29 recipients of living related liver transplants. Insulin levels did not change significantly throughout this study, while glucagon levels decreased immediately after reperfusion, indicating a rapid degradation of glucagon by the graft liver. The insulin/glucagon (I/G) ratio increased after reperfusion concomitantly with AKBR. In addition, the I/G ratio was significantly correlated with AKBR after reperfusion. It is concluded that the increase in the I/G ratio was closely related to the recovery of graft liver function as reflected by the AKBR in living related liver transplantation.

Necrolytic migratory erythema without glucagonoma in patients with liver disease

BACKGROUND

Necrolytic migratory erythema (NME) is an uncommon inflammatory dermatosis with a distinct clinical and histologic appearance. NME is usually associated with glucagonoma. Only a few cases of NME in the absence of glucagonoma have been previously reported.

OBJECTIVE

We sought to understand further the pathogenesis of NME by analyzing data from three patients.

METHODS

Three patients were examined both clinically and histopathologically.

RESULTS

Each patient had an extensive erythematous scaling eruption in intertriginous, perioral, and acral areas, and a markedly red, smooth tongue. Skin biopsy specimens showed confluent parakeratosis, epidermal pallor, papillary edema, and a lymphohistiocytic infiltrate. Two patients had alcoholic liver disease and one had liver dysfunction as a result of hemochromatosis. Serum albumin level was depressed, and liver enzyme values were increased in all three patients. Glucagonoma was undetectable in these patients.

CONCLUSION

In the absence of glucagonoma, hepatocellular dysfunction and hypoalbuminemia appear to be the most common factors associated with NME.

Vasodilatory state of decompensated cirrhosis: relation to hepatic dysfunction, ascites, and vasoactive substances

The objective of this study was to determine the relations between the hallmark circulatory finding of decompensated cirrhosis, a reduced systemic vascular resistance (SVR), and the indices of hepatic decompensation, the accumulation of ascites, and the concentrations of various vasoactive substances. At a university-affiliated teaching hospital, eighteen hospitalized patients with cirrhosis and 18 age- and sex-matched healthy subjects were used. This was a case-control study. Measurements included cardiac dimensions and indices derived from echocardiograms and Doppler studies, abdominal ultrasound estimates of ascites, indices of hepatic function, and various serum (S) and urinary (U) substances. Results showed that cirrhotics had increased left atrial and left ventricular dimensions, left ventricular mass, heart rate, cardiac output (CO), transvalvular velocities, and a decreased SVR. SVR was related to hepatic dysfunction, as reflected by an abnormal prothrombin time ratio (r = -0.64, p = 0.006), and also related to overall severity of liver disease as estimated by the Child-Pugh score (r = -0.53, p = 0.044). Although cirrhotics with ascites generally had a reduced SVR, estimates of ascites were directly related to SVR (r = 0.57, p = 0.03) and inversely related to CO (r = -0.53, p = 0.04). Concentrations of S and U digoxin-like immunoreactive substance (DLIS) were also increased, but the concentrations of S glucagon and estradiol were not elevated. The accumulations of S and U DLIS, S glucagon, and S estradiol were all related to hepatic dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of portal vein stenosis and superior mesenteric vein ligation on mesenteric venous pressure and porta-systemic shunting in the rat

We studied the relative contributions of splanchnic congestion and porta-systemic shunting to the maintenance of experimental portal venous hypertension. Three groups of rats were prepared: portal vein-stenosed, superior mesenteric vein-ligated and sham operated. Though elevated in both operated groups compared to controls, mesenteric venous pressure was highest in the portal vein-stenosed animals (PV vs SMV vs Sham: 19.6 +/- 1.3 vs 15.6 +/- 0.7 vs 13 +/- 0.6; p < .05 PV and SMV vs Sham, and PV vs SMV) despite the presence of 50% porta-systemic shunting in the portal vein-stenosed animals. Shunting was negligible in the other two groups. Peripheral plasma glucagon and vasoactive intestinal peptide (VIP) levels were similar in all three groups. We conclude that mesenteric congestion alone plays a minor role in the pathogenesis of portal hypertension, which may instead be related to the porta-systemic shunting of vasoactive substances other than glucagon and VIP.

Diabetes mellitus in patients with liver cirrhosis

In spite of the high prevalence of diabetes mellitus (DM) in patients with liver cirrhosis (LC) few studies have focused on the clinical implications of this association. We investigated the clinical and pancreatic-endocrine features of 34 patients who developed DM after LC (Group I). Results were compared with 34 carefully matched patients with only Type II DM (Group II). A standard meal test was performed in 26 patients with normal renal function from each group to assess beta-cell function. Group I patients, less frequently had retinopathy (14.7% vs. 45.5%, P < 0.05) and a family history of diabetes (23.5% vs. 58.8%, P < 0.01). Group I patients also showed signs of enhanced insulin resistance, reflected by higher insulin dose requirements in insulin-treated patients (0.87 +/- 0.10 vs. 0.62 +/- 0.05 IU/kg/day, P < 0.01) and increased basal C-peptide values (0.88 +/- 0.06 vs. 0.68 +/- 0.07 pmol/l, P < 0.05, respectively) than those in Group II. These results suggest that several clinical features, probably related to the hepatopathy, define DM occurring in patients with LC.

Impaired function of pancreatic islets from rats with portal hypertension resulting from cirrhosis and partial portal vein ligation

Increased circulating insulin and glucagon levels are a common observation in patients with cirrhosis, as well as in portal hypertensive models. Hyperinsulinemia and hyperglucagonemia may be caused either by increased beta- and alpha-cell secretion or by defective hepatic clearance of these hormones. To elucidate whether an abnormal endocrine pancreatic function might contribute to the hyperinsulinism or to the hyperglucagonism observed in chronic portal hypertension, insulin and glucagon secretion were measured in vitro in isolated pancreatic islets from rats with partial portal vein ligated and rats with cirrhosis caused by carbon tetrachloride poisoning. Both rats with partial portal vein ligation and rats with cirrhosis caused by carbon tetrachloride poisoning exhibited hyperinsulinism and hyperglucagonism as compared with control rats. Isolated pancreatic islets from both experimental portal hypertensive models showed an impaired insulin secretion after glucose stimulation. On the contrary, glucagon secretion was significantly increased, and there was a markedly enhanced response to arginine. This increased in vitro glucagon production could not be corrected, even in the presence of high glucose concentrations in the incubation medium. Therefore our data show that although hyperglucagonism in rats with partial portal vein ligation and in rats with cirrhosis caused by carbon tetrachloride poisoning is promoted by an enhanced alpha-cell secretion, hyperinsulinism is associated with impaired beta-cell secretion.

Failure of glucagon to stimulate hepatic glycogenolysis in well-nourished patients with mild cirrhosis

The ability of glucagon to stimulate hepatic glucose production (HGP) was studied in clinically stable cirrhotic patients (n = 8) who had, based on long-term follow-up evaluation, relatively good liver function (Child-Pugh A) and whose dietary intake and physical characteristics were comparable to those of healthy control subjects (n = 8). Plasma glucagon concentration was slightly but not significantly increased in cirrhotic patients versus control subjects in the basal state (190 +/- 41 v 126 +/- 24 pg/mL, P = NS) and during a continuous 180-minute glucagon infusion at 3 ng/kg/min (349 +/- 56 v 243 +/- 37, P = NS). The increment in plasma glucagon level (+164 +/- 57 v +127 +/- 35, P = NS) also was slightly greater in the cirrhotic group. HGP (measured with [6-3H]-glucose) in the basal state was similar in cirrhotic and control subjects (1.79 +/- 0.09 v 1.94 +/- 0.15 mg/kg/min, P = NS). In cirrhotic patients, stimulation of HGP by glucagon was blunted during the first 15 to 30 minutes of the infusion period (representing glucagon's predominant effect on glycogenolysis; 0.23 +/- 0.20 v 1.06 +/- 0.19 mg/kg/min, P < .05), but it was not different from that in control subjects during the remaining course of the experiment (30 to 180 minutes). Basal plasma insulin and C-peptide concentrations did not change from baseline during the glucagon infusion in cirrhotics, whereas they increased slightly but not significantly in controls. These data demonstrate that even in the early stages of cirrhosis, the liver is resistant to the stimulatory effect of glucagon on hepatic glycogenolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic regulation of pancreatic alpha-cell function

The direct feedback regulation between the endocrine gland and its target organ is an expected biological relationship. However, such a phenomenon is far from being well established in the case of the endocrine pancreas and its major target organ, the liver, especially since plasma glucose has been established as the prime regulator. In this perspective, I have reexamined the feedback regulation between plasma glucose and glucagon secretion by the pancreatic alpha cell. Surprisingly, available data in the literature appear to document a frequent breakdown of this well-established interdependence between plasma glucose and pancreatic alpha cells, as reflected by a sustained elevation of plasma glucagon levels in several physiologic and pathologic states with concurrent euglycemia or hyperglycemia. Moreover, normal or low glucagon concentrations in the presence of fasting hypoglycemia in patients with insulinoma or non-islet cell tumors secreting insulin-like peptides and in patients with hepatic glycogen storage disorders may enhance our hypothesis that plasma glucose level may not be the major regulator of glucagon secretion. Extensive data in the literature show that hyperglucagonemic states are characterized by a unique metabolic environment, namely hepatic glycogen depletion. Similarly, hepatic glycogen stores are abundant in the presence of normal or low glucagon concentrations. These findings imply a distinct relationship between hepatic glycogen content and plasma glucagon level.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential evaluation of islet cell responses to glucose in the transplanted pancreas in humans

We evaluated the hormonal and metabolic responses of denervated pancreas allografts in nine volunteers 3 to 12 months after the transplant (initial) and again 1 year later (follow-up). Eight of the patients received simultaneous pancreas-kidney transplants. The glucose clamp technique was used to create a square wave of hyperglycemia 5.5 mmol/L above the basal glucose level for 2 hours. A biphasic insulin response was evident in each subject, both initially and at follow-up. The initial plasma insulin response was fourfold higher in patients with pancreas-kidney transplants than in normal volunteers. However, the plasma insulin response of the patients with pancreas-kidney transplants at the follow-up study was more similar to that of the normal controls. The plasma glucagon levels were elevated in follow-up clamp studies. Hepatic glucose production and glucose disposal were similar in both studies. At the follow-up examination only, GLUT4, the major insulin-sensitive glucose transporter, was measured in muscle homogenates by immunoblotting. GLUT4 levels in the patients with pancreas-kidney transplants were only 55% as abundant as in normal volunteers. This may be due, in part, to immunosuppressive therapy or to persistent, albeit reduced, levels of hyperinsulinemia even 2 years after transplantation. We concluded that, despite systemic drainage of the pancreas and immunosuppressive therapy, pancreatic insulin secretion, peripheral insulin levels, and muscle insulin responsiveness are restored toward normal levels approximately 2 years after the transplant.

Effects of somatostatin on renal function in cirrhosis

To investigate the renal effects of somatostatin in cirrhosis, renal function and plasma and urinary levels of endogenous neurohumoral vasoactive substances were measured in conditions of intravenous water overload (20 mL/kg body wt with 5% glucose) before and during the intravenous infusion of somatostatin (250-500 micrograms/h) in 6 cirrhotic patients without ascites and 17 nonazotemic cirrhotic patients with ascites. Somatostatin induced a significant reduction of renal plasma flow, glomerular filtration rate, and free water clearance in both groups of patients. In patients with ascites, somatostatin also reduced urinary sodium excretion. Changes in renal function were significantly more marked in patients with ascites than in those without ascites and occurred in the absence of changes in mean arterial pressure and plasma levels of renin, aldosterone, norepinephrine, antidiuretic hormone, and atrial natriuretic peptide. Somatostatin induced a significant reduction in the plasma concentration of glucagon and urinary excretion of prostaglandin E2 that was not related to changes in renal function. These findings indicate that somatostatin administration induces renal vasoconstriction and impairs glomerular filtration rate, free water clearance, and sodium excretion in cirrhosis by a mechanism unrelated to systemic hemodynamics and endogenous neurohumoral vasoactive systems.

Glucagon-independent renal hyperaemia and hyperfiltration after an oral protein load in Child A liver cirrhosis

The work was designed to study the effects of a meat meal on glomerular filtration rate (GFR), renal plasma flow (RPF), and plasma concentrations of glucagon, insulin, growth hormone, renin, aldosterone, total amino acids, and NH3 in healthy humans (H) as well as in patients with Child A liver cirrhosis (LC). The meat meal produced renal hyperaemia and hyperfiltration without changes in the filtration fraction. Fractional Na excretion in urine increased significantly after the meat meal only in LC. Hyperinsulinaemia and hyperglucagonaemia were seen at baseline in LC and were not affected by the meat meal, whereas in H glucagon concentration increased significantly over baseline within 30 min from the meat meal and insulin within 60 min. Growth hormone concentration was normal at baseline in LC and increased significantly 120-180 min after the meal, whereas it was not affected in H. Renin and aldosterone were stable in both H and LC. Plasma amino acid concentration began to increase 60 min after the meat meal, when hyperfiltration was present. The data indicate that in human Child A cirrhosis of the liver renal haemodynamic response to a meat meal is independent of changes in glucagon.

Circulatory changes induced by portal venous diversion and mesenteric hypertension in rats

We studied the hemodynamics in four groups of rats with combinations of mesenteric hypertension and portal diversion. Operations created three groups with mesenteric hypertension and different degrees of portal venous diversion: mesenteric vein stenosis, portal vein stenosis and end-to-side portacaval anastomosis with mesenteric vein stenosis, the fourth group had only portacaval anastomosis. A control group had sham operations. Cardiac output, splanchnic blood flows and portosystemic shunt indices were measured with radioactive microspheres. Mesenteric venous pressures in the mesenteric-stenosed, portal-stenosed, portacaval-shunted and end-to-side portacaval anastomosis with mesenteric vein stenosis rats were, respectively, 13.5 +/- 0.6, 15.3 +/- 0.7, 4.3 +/- 0.5 and 13.0 +/- 0.9 mm Hg, which were all significantly different from controls: 8.3 +/- 0.3 mm Hg. Portosystemic shunt indices were also significantly different from each other: controls, 0.4% +/- 0.02%; mesenteric-stenosed, 5.9% +/- 2.3%; and portal-stenosed, 52.1% +/- 4.9%. Cardiac output and splanchnic visceral blood flows were significantly increased in the portal-stenosed rats and the two groups with portacaval anastomoses, with the latter two groups having the highest values. The addition of mesenteric stenosis did not change the blood flows because mesenteric-stenosed rats did not differ from controls and end-to-side portacaval anastomosis with mesenteric vein stenosis rats did not differ from rats with portacaval anastomosis alone. These results suggest that mesenteric venous hypertension per se does not affect hemodynamics but that diversion of portal venous blood from the liver is a critical factor in the development of hyperkinetic circulation in portal hypertension.

Insulin and glucagon infusion in acute alcoholic hepatitis: a prospective randomized controlled trial

In a randomized, controlled trial to investigate the possible benefit of insulin and glucagon therapy in severe acute alcoholic hepatitis, 86 patients were randomized to receive 30 U insulin and 3 mg glucagon in 250 ml 5% dextrose over 12 hr each day for 3 wk or a similar regime of identical placebo. No significant differences were seen in patients' clinical characteristics and disease severity in the treated and placebo groups. Of the 43 patients receiving insulin and glucagon, 15 (35%) died within 4 wk of randomization, compared with 14 deaths (33%) in the control patients (p = not significant). When the patients surviving the first 4 wk were examined there were five more deaths in the treatment group, compared with one death in the control group at 6-mo follow-up (p = not significant). No significant differences in the frequency of short-term or long-term complications of alcoholic liver disease or relapse to alcohol were seen when the two groups were compared, although hypoglycemia was seen in six patients during infusion of insulin and glucagon. Similarly, no significant differences were seen in the improvement in clinical or biochemical features at 4 wk and at 6 mo in survivors when the insulin and glucagon-treated patients were compared with patients in the placebo group. This study does not confirm previous reports that insulin and glucagon infusion improves the outcome of severe acute alcoholic hepatitis.

Necrolytic migratory erythema without glucagonoma versus canine superficial necrolytic dermatitis: is hepatic impairment a clue to pathogenesis?

The case of a 57-year-old diabetic man with necrolytic migratory erythema in the absence of glucagonoma is reported. The clinical and pathologic features of his dermatitis and subsequent clinical course are compared with those of canine superficial necrolytic dermatitis, an unusual cutaneous necrotizing eruption of dogs that is identical histologically to necrolytic migratory erythema. In addition to a necrolytic dermatitis, both our patient and most dogs with superficial necrolytic dermatitis have diabetes mellitus and hepatic failure in the absence of glucagonoma. Thus hyperglucagonemia most likely is not a factor in the origin of the necrotizing dermatitis in this patient or in dogs. The role of hepatocellular dysfunction in the pathogenesis of necrolytic migratory erythema and superficial necrolytic dermatitis is considered.

Hemodynamic effects of somatostatin in the rat: relationship with plasma glucagon levels

Hepatic, splanchnic, and systemic hemodynamic effects of somatostatin infusion, as well as changes in plasma glucagon concentration, were studied in normal rats, using techniques involving radioactive microspheres and radioimmunoassay. Somatostatin infusion caused a decrease in arterial blood flow to the stomach, small intestine and spleen, with the net effect of reducing hepatic portal blood flow and portal pressure. The hepatic arterial blood flow was not altered. The systemic hemodynamic effects of somatostatin were slight, although renal blood flow diminished, Plasma glucagon concentration did not vary immediately after somatostatin infusion. The mechanism of the hemodynamic action of the hormone is not yet clear, but in normal conditions it is not related to the inhibition of glucagon secretion.

Glucagon, catecholamine and pancreatic polypeptide secretion in type I diabetic recipients of pancreas allografts

Successful pancreas transplantation in type I diabetic patients restores normal fasting glucose levels and biphasic insulin responses to glucose. However, virtually no data from pancreas recipients are available relative to other islet hormonal responses or hormonal counterregulation of hypoglycemia. Consequently, glucose, glucagon, catecholamine, and pancreatic polypeptide responses to insulin-induced hypoglycemia and to stimulation with arginine and secretin were examined in 38 diabetic pancreas recipients, 54 type I diabetic nonrecipients, and 26 nondiabetic normal control subjects. Glucose recovery after insulin-induced hypoglycemia in pancreas recipients was significantly improved. Basal glucagon levels were significantly higher in recipients compared with nonrecipients and normal subjects. Glucagon responses to insulin-induced hypoglycemia were significantly greater in the pancreas recipients compared with nonrecipients and similar to that observed in control subjects. Glucagon responses to intravenous arginine were significantly greater in pancreas recipients than that observed in both the nonrecipients and normal subjects. No differences were observed in epinephrine responses during insulin-induced hypoglycemia. No differences in pancreatic polypeptide responses to hypoglycemia were observed when comparing the recipient and nonrecipient groups, both of which were less than that observed in the control subjects. Our data demonstrate significant improvement in glucose recovery after hypoglycemia which was associated with improved glucagon secretion in type I diabetic recipients of pancreas transplantation.

Hemodynamic effects of glucagon in portal hypertension

It has been suggested that glucagon contributes to the pathogenesis of portal hypertension by increasing portal blood flow. This study examined this issue by assessing the hemodynamic effects of a pharmacological dose of glucagon (1 mg, intravenously) in patients with cirrhosis and portal hypertension (n = 10) and in subjects without significant liver disease (controls = n = 5). Patients with cirrhosis had much higher glucagon levels than control subjects (875 +/- 167 vs. 186 +/- 25 pg/ml, p less than 0.01) and showed blunted hemodynamic responses after glucagon administration. This occurred despite greater circulating glucagon levels, probably because of a significant prolongation of the plasma half-life of exogenously administered glucagon (4.9 +/- 0.4 vs. 2.7 +/- 0.1 min, p less than 0.1). Control subjects had marked increases in heart rate (+ 19% +/- 4%, p less than 0.01), cardiac index (+ 16% +/- 4%, p = 0.01) and arterial pressure (+ 10% +/- 3%, p less than 0.05), but corresponding changes in patients with cirrhosis (+ 7% +/- 1%, + 6% +/- 1%, and + 6% +/- 2%, respectively) were significantly less pronounced (p = 0.05), and there was a negative correlation between basal glucagon levels and the response of heart rate to glucagon injection (r = -0.804, p less than 0.001). Resistance to the systemic effects of glucagon in cirrhosis may thus be caused by a down-regulation of vascular glucagon receptors. In addition, glucagon administration caused a significant increase in portal pressure (from 18.1 +/- 1.1 to 19.0 +/- 1.2 mm Hg, p less than 0.01), as well as in azygos blood flow (from 0.54 +/- 0.03 to 0.64 +/- 0.04 L/min, + 19% +/- 4%, p less than 0.02), reflecting increased portocollateral blood flow. These findings are consistent with the hypothesis that glucagon is one of the factors contributing to the splanchnic vasodilatation and increased portal pressure of cirrhosis.