Evidence for an augmented glucagon dependence of hepatic glucose production in cirrhosis of the liver

The role of endogenous glucagon in maintaining hepatic glucose production after an overnight fast in patients with cirrhosis of the liver was studied with arterial-hepatic-venous catheterization and using somatostatin to suppress glucagon secretion. Arterial glucagon levels were elevated in eight cirrhotics to 290 +/- 90 pg/ml (SEM) compared to 100 +/- 10 pg/ml (P less than 0.02) in five normal controls, and they were lowered during administration of somatostatin (SRIF; 250 microgram/h) by a mean of 154 pg/ml and 39 pg/ml in cirrhotics and controls, respectively. Basal net splanchnic glucose production (NSGP) was similar in patients with and without cirrhosis (approximately 100 mg/min) but declined more markedly during 30 min of SRIF in cirrhotics to a net splanchnic uptake of glucose of 30 +/- 20 ml/min, as opposed to a fall of NSGP by 44 +/- 2 mg/min in controls (P less than 0.01). To assure that NSGP declined during SRIF infusion due to the fall of glucagon levels, SRIF was combined with a glucagon infusion at 150 ng/m2 . min in four cirrhotics and in five control subjects. Arterial glucagon levels were elevated to a mean of 650 pg/ml and 559 pg/ml in cirrhotics and controls, respectively. NSGP increased after 40 min of SRIF and glucagon replacement to 179 +/- 33 mg/min in cirrhotics and significantly more, to 412 +/- 68 mg/min, in controls (P less than 0.01). Thus, hepatic glucose production during basal and elevated glucagon levels suggested hepatic resistance to glucagon in cirrhosis. Nevertheless, endogenous glucagon played an augmented stimulatory role in maintaining glucose production in the normal range since there was an exaggerated fall of hepatic glucose output during glucagon suppression.     

Thyrotropin-releasing hormone (TRH)-induced growth hormone (hGH) responses in cirrhotic men.

The plasma growth hormone (hGH) responses to an intravenous challenge of 400 micrograms of thyrotropin-releasing hormone (TRH) were evaluated in 14 normal controls and in 29 chronic alcoholic men. The normal controls had either a minimal or no hGH response to TRH, having basal hGH levels of 0.9 +/- 0.2 ng per ml and peak hGH levels of 2.0 +/- 0.5 ng per ml. In contrast, the chronic alcoholic men had a basal hGH level of 2.8 +/- 0.4 ng per ml, 3 times the basal level of the normal controls (P less than 0.01). The peak hGH response of the alcoholic men was 7.4 +/- 1.5 ng per ml (P less than 0.01). The 29 alcoholic men could be divided into two groups based upon the presence or absence of cirrhosis as determined by liver biopsy. The 16 alcoholic men with cirrhosis had greater basal hGH levels (3.5 +/- 0.6 ng per ml) and peak hGH levels (9.5 +/- 2.3 ng per ml) than did the 13 alcoholic men without cirrhosis (basal hGH 2.1 +/- 0.6 ng per ml, peak hGH 4.9 +/- 1.5 ng/ml). Plasma estradiol levels were similar in the normal controls and in the alcoholic men. In contrast, plasma estrone was greater in the alcoholic men (32.2 +/- 3.5 pg per ml) than in the normal controls (18.9 +/- 1.8 pg per ml) (P less than 0.05). However, when the plasma estrone levels of alcoholic men with cirrhosis were compared to those of the alcoholic men without cirrhosis no difference existed. Thus it is difficult to ascribe the increased hGH responses of the cirrhotic alcoholic men when compared to those of the noncirrhotic alcoholic men as being a result of increased basal estrogen levels.     

Gallbladder emptying and somatostatin and cholecystokinin plasma levels in celiac disease

OBJECTIVE: Gallbladder hypomotility in celiac disease has been attributed to decreased cholecystokinin secretion. The possible influence of somatostatin, which inhibits gallbladder motility, however, has never been evaluated. In this study gallbladder emptying and cholecystokinin and somatostatin plasma levels were evaluated in response to a fatty meal in patients with celiac disease at diagnosis and after long-term gluten-free diet and in controls. METHODS: Gallbladder volume and plasma levels of cholecystokinin and somatostatin were measured by ultrasonography and radioimmunoassay, respectively, at 0 time and 30, 60, 75, and 90 min after an oral fatty meal (227 kcal, 45% fat) in 10 celiac patients at diagnosis and after 18 months of successful gluten-free diet and in 10 healthy subjects. The pattern of gallbladder emptying was evaluated by mixed factorial analysis of variance and the curve fitting by multiple regression analysis. RESULTS: Patients at diagnosis had significantly greater fasting gallbladder volume and higher somatostatin plasma levels than controls (25.7 +/- SD 9.7 ml vs 16.8 +/- 7.0 ml, p = 0.021 and 9.3 +/- 4.6 vs 4.8 +/- 3.4 pmol/L, p = 0.023, respectively), significantly lower fatty meal-induced gallbladder ejection fraction (55 +/- 11.2% vs 76 +/- 7.2%, p = 0.005), and cholecystokinin peak and smaller area under the cholecystokinin secretion curve (3.1 +/- 2.3 pmol/L vs 10.5 +/- 6.9 pmol/L, p = 0.028 and 157 +/- 142 pmol/L/90 min vs 453 +/- 229 pmol/L/90 min, p = 0.028, respectively). The two groups had a similar emptying pattern (p = 0.8913) expressed by a significant quadratic term of the emptying function (p = 0.0001). The mean overall emptying volume was significantly greater in patients than in controls (p = 0.0007). Gluten-free diet normalized these findings. CONCLUSIONS: In patients at diagnosis, elevated somatostatin levels were associated with increased gallbladder fasting volume, whereas decreased cholecystokinin secretion was responsible for the reduced gallbladder emptying. Gluten-free diet reversed these abnormalities.     

Effects of autogenous reinfusion of ascitic fluid on plasma atrial natriuretic peptide and renin activity in cirrhotic patients]

Acute volume loading produced by autogenous reinfusion of ascitic fluid provides an ideal volume expansion model for studying hormonal regulation and it was carried out in 10 cirrhotic patients with massive ascites. The basal plasma ANP level in the cirrhotic patients with ascites was 1776.00 +/- 160.72 ng/L, which was significantly elevated as compared with the level in normal controls (378.36 +/- 39.58 ng/L, P less than 0.01), PRA was significantly higher in patients with ascites (5.13 +/- 0.18 micrograms/l/h) than in healthy volunteers (1.46 +/- 0.31 micrograms/l/h, P less than 0.01). During reinfusion of ascitic fluid there was a significant natriuresis and diuresis; ANP rose from a basal mean value to a peak value of 2166.00 +/- 195.70 ng/l (P less than 0.05) at periinfusion. Subsequently, ANP dropped at 1 hour after infusion (1819.00 +/- 165.92ng/L, P less than 0.05), PRA dropped progressively from a mean basal level to that of 2.48 +/- 0.58 micrograms/l/h (P less than 0.05) at periinfusion. These data demonstrate that there is no evidence for absolute deficiency of ANP in cirrhosis with ascites. The immediate diuresis and natriuresis were associated with a rise in ANP, but the sustained renal consequences may be possibly connected with suppression of RAAS.     

Circulating somatostatin concentrations in healthy and cirrhotic subjects

Plasma insulin, glucagon, somatostatin, and glucose concentrations were measured in the fasting state as well as after mixed meals (breakfast, lunch, and dinner) in 10 cirrhotic patients and 10 control subjects during a 24-hour period. Cirrhotic patients had fasting glucose values higher than controls (at -15 min: 5.2 +/- 0.2 mmol/L v 3.9 +/- 0.5 mmol/L, P less than 0.05; at 0 min: 5.5 +/- 0.3 mmol/L v 4.3 +/- 0.5 mmol/L, P less than 0.01). After meals blood glucose values remained higher in cirrhotics than in controls. Insulin levels did not differ between the groups in the fasting state, but cirrhotics showed a lower response to meals. Corresponding glucagon concentrations were greater in cirrhotics than in controls before and after meals throughout the 24-hour period (from -15 min to 24 hour: P less than 0.01). BAsal plasma somatostatin levels in the cirrhotic group were significantly higher than in control subjects (at -15 min and at 0 min: P less than 0.05) and further increased after meals. Plasma somatostatin was heterogeneous in normal and cirrhotic group, but the increase in its concentrations in patients with chronic liver disease was for the most part a consequence of elevations in the 1600 and 3500 molecular weight components. The half-life of exogenously infused somatostatin in cirrhotics was comparable to that of controls. These results indicate that in liver cirrhosis elevated levels of circulating somatostatin are associated with hyperglucagonemia and impaired insulin release. The high plasma somatostatin levels observed in cirrhotic patients are the result of hypersecretion of the D cell rather than impaired removal of the peptide.     

Plasma concentrations of atrial natriuretic hormone in acromegaly: relationship to hypertension.

Atrial natriuretic hormone is involved in the control of blood pressure and water-electrolyte balance. In order to assess the relationship between atrial natriuretic hormone and hypertension in acromegaly, 34 subjects were studied, 18 with acromegaly (10 normotensive and 8 hypertensive) and 16 healthy controls. Plasma atrial natriuretic hormone levels, as well as plasma renin activity, aldosterone and growth hormone levels were measured in basal conditions in all subjects. Additionally, plasma renin activity and aldosterone levels were determined after standard stimulation. In hypertensive acromegalic patients, atrial natriuretic hormone plasma concentrations (39.8 +/- 3.5 ng/l) were significantly higher than in patients without hypertension (27.9 +/- 4.1 ng/l), and in controls (28.6 +/- 1.3 ng/l) (p less than 0.01 in both comparisons). Stimulated plasma renin activity values were decreased in hypertensive acromegalic patients when compared with those in normotensive patients (1.14 +/- 0.29 vs 4.03 +/- 0.66 micrograms.l-1.h-1, p less than 0.01). In acromegaly, atrial natriuretic hormone levels correlated with mean arterial pressure (r = 0.58, p = 0.01). These results suggest that atrial natriuretic hormone plasma levels are slightly increased in patients with acromegaly and hypertension.     

Helicobacter pylori-related hypergastrinaemia is not due to elevated antral surface pH. Studies with antral alkalinisation.

It has been postulated that Helicobacter pylori-related hypergastrinaemia is due to bacterial ammonia raising antral surface pH and thus preventing acid inhibition of gastrin release. If true, the infection should not alter gastrin release at neutral intragastric pH. To test this, we have studied basal and meal-stimulated gastrin at uncontrolled pH and at pH greater than 6 in duodenal ulcer patients before and after eradication of H. pylori. The median integrated gastrin response to the meal alone was 2525 ng/l.min (range, 550-8725) before and 725 ng/l.min (range, 250-2925) after eradication of H. pylori (p less than 0.01). The corresponding values when intragastric pH was maintained above 6 were 3700 ng/l.min (range, 1900-14,100) and 1400 ng/l.min (range, 400-3400) (p less than 0.01). The median reduction in gastrin after eradication of H. pylori was thus similar when the meal was taken at uncontrolled pH (61%; range, 0-97%) and at pH greater than 6 (69%; range, 36-89%). Likewise, 5 h of gastric alkalinisation did not cause the basal gastrin values when H. pylori was eradicated to increase to those observed when H. pylori was present. These findings indicate that the hypergastrinaemia is not due to elevated antral surface pH.     

Somatostatin in the elderly: diurnal plasma profile and secretory response to meal stimulation

Plasma somatostatin levels were determined during a 24-hour period and after a meal test in 7 and 5 elderly subjects (76-90 years), respectively. The data obtained were compared with those recorded in young adult subjects (22-30 years). Increased basal somatostatin values were found in elderly subjects (20.0 +/- 1.5 pg/ml) when compared to young adults (14.1 +/- 0.6 pg/ml; p less than 0.01). Also, the mean 24-hour somatostatin levels were higher in the elderly (21.3 +/- 0.8 pg/ml) than in young adults (16.7 +/- 0.5 pg/ml; p less than 0.01), and minor diurnal variations were found in the former group. The response to the meal test was less evident in the elderly than in the control group. The data obtained indicate an increased basal somatostatin production associated with a diminished variability throughout the 24-hour period and in relation to meals.     

Effect of somatostatin on splanchnic hemodynamics in patients with cirrhosis of the liver and in normal subjects

The effect of somatostatin on splanchnic hemodynamics was determined in 8 patients with cirrhosis of the liver and in 18 normal subjects using arterial-hepatic-venous catheterization. Estimated hepatic blood flow determined by indocyanine green infusion was 1.36 +/- 0.23 L/min (+/- SEM) in patients with cirrhosis and remained unaffected during 30 min of somatostatin (250 microgram/h) administration. Wedged hepatic venous pressure which was elevated to 23 +/- 1.8 mmHg was also uninfluenced. In contrast to somatostatin, an infusion of vasopressin (12 U/h for 30 min) given to the same patients, lowered estimated blood flow by 28% (p < 0.05) and wedged hepatic venous pressure by 18% (p < 0.02). Arterial gastrin and insulin levels were lowered during somatostatin infusion by 33% (p < 0.02) and by 75% (p < 0.005), respectively. In contrast to the cirrhosis, infusion of 250 microgram/h somatostatin into normal subjects was associated with a decrease of estimated hepatic blood flow from 1.20 +/- 0.16 to 0.88 +/- 0.12 L/min (p < 0.01) representing a 27% decline. Arterial gastrin and insulin concentrations were lower (p < 0.01) than in cirrhosis, but the basal levels were lowered by somatostatin to a similar degree in both groups of patients. A higher dose of somatostatin (500 microgram/h) administered to normal subjects resulted in a similar decrease of gastrin and of estimated hepatic blood flow as that seen with 250 microgram/h, whereas a lower dose (125 microgram/h) decreased gastrin but failed to influence estimated hepatic blood flow. Thus, somatostatin at a dose which has been used in the treatment of acute peptic ulcer hemorrhage (250 microgram/h) failed to influence estimated hepatic blood flow and wegded hepatic venous pressure in patients with cirrhosis but lowered splanchnic blood flow in normal subjects. Assuming that this effect contributes to somatostatin's therapeutic efficacy, these results cast doubt on its potential value in the treatment of upper gastrointestinal bleeding of cirrhotics with portal hypertension.     

Androgen and estrogen response to adrenal and gonadal stimulation in idiopathic hemochromatosis: evidence for decreased estrogen formation

Gonadal function in idiopathic hemochromatosis (IHC) was evaluated by comparing clinical features and levels of sex hormones in 10 male patients with IHC (cirrhosis, 4; fibrosis, 6), 6 male patients with alcoholic cirrhosis (AC) and 10 healthy, age-matched controls. Impotence was present in 9 IHC and all AC patients and was associated with decreased plasma testosterone levels. However, gynecomastia, a feature in all patients with AC, was not present in IHC, and plasma sex hormone binding globulin was normal. Patients with IHC showed significantly lower basal estradiol levels (17.7 +/- 6.3 pg per ml) than did controls (28.5 +/- 8.5 pg per ml), and low LH levels (p less than 0.01), which were insufficiently stimulated by luteinizing hormone releasing hormone (n = 8) as well as a decrease in prolactin concentration (2.9 +/- 1.4 vs. 5.9 +/- 1.9 ng per ml in the controls) suggesting pituitary failure. Synthesizing capacity of sex hormones was determined by adrenocorticotropic hormone and human chorionic gonadotropin administration. Basal and stimulated levels of androstenedione and cortisol indicated normal function of the adrenals in IHC. However after adrenocorticotropic hormone, estrone levels increased to only 16.2 +/- 8.4 pg per ml (controls, 27.3 +/- 4.7 pg per ml; p less than 0.01). Increments of estrone (12.5 +/- 9.2 pg per ml) and estradiol (17.9 +/- 11.6 pg per ml) were also lower in IHC following human chorionic gonadotropin administration than in controls (26.0 +/- 7.2 and 37.5 +/- 11.4 pg per ml, respectively). In contrast, plasma human chorionic gonadotropin raised testosterone levels 3.3-fold in IHC and 2.2-fold in controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of somatostatin-induced insulinopenia on glucose oxidation in man

In the basal state the body utilizes glucose at a rate of 2.2 - 2.3 mg.kg-1.min-1; of this approximately 1.2 - 1.3 mg.kg-1.min-1 is oxidized, while the remaining 1.0 mg.kg-1.min-1 must be utilized by non-oxidative pathways. Little information is, however, available concerning the insulin dependency of these processes. To examine the role of basal insulin levels on glucose oxidation, glucose storage and total body glucose uptake, somatostatin (10 microgram/min) was infused for 2 h in nine volunteers while maintaining plasma glucose concentration constant at basal levels by an exogenous glucose infusion. Basal plasma insulin fell by about 50% (13 +/- 2 to 7 +/- 1 mU/l, p less than 0.01). Total body glucose metabolism (3H-3-glucose) declined from 2.3 +/- 0.1 to 1.9 +/- 0.1 mg.kg-1.min-1 (p less than 0.01). This decrease was entirely accounted for by a fall in basal glucose oxidation (measured by indirect calorimetry) from 1.3 +/- 0.1 to 0.7 +/- 0.1 mg.kg-1.min-1 (p less than 0.001). To assess the specific role of insulin deficiency in the decline in glucose oxidation, subjects were restudied with somatostatin plus basal insulin replacement (0.07 mg.kg-1.min-1). Fasting insulin concentration (14 +/- 1 mU/l) remained constant during somatostatin plus insulin infusion (13 +/- 1 mU/l) and basal rates of glucose oxidation (1.2 +/- 0.1 mg.kg-1.min-1) and total body glucose uptake did not change significantly. After 2 h, the basal insulin infusion was stopped and somatostatin was continued. Over the subsequent hour, glucose oxidation declined by 0.4 +/- 0.1 mg.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of insulin resistance in Turner syndrome

The characteristics of insulin resistance, in Turner syndrome are still unclear. For this purpose in 4 patients with Turner syndrome and in 8 control females we performed an euglycaemic hyperinsulinemic glucose clamp at the following insulin infusion rates (50 and 100 mU/Kg x h), each period lasting 120 min. A simultaneous infusion of D-3-H-glucose allowed us to determine in basal conditions and during the clamp hepatic glucose output and glucose disappearance rate (Rd). In basal conditions plasma glucose (4.8 +/- 0.1 vs 4.6 +/- 0.2 mmol/1 p = NS) and plasma glucagon (102 +/- 7.5 vs 112 +/- 11.3 ng/l p = NS) were similar in both groups despite higher plasma insulin (19 +/- 1.8 vs 7 +/- 2.2 mU/l p less than 0.05) and C-peptide (1.0 less than 0.1 vs 0.8 +/- 0.06 pmol/l p less than 0.05) levels in patients with Turner syndrome. In the last 60 min of the lower insulin infusion rate glucose infusion rate (4.1 +/- 0.3 vs 2.9 +/- 0.4 mg/Kg x min p less than 0.05) and glucose disappearance rate (3.89 +/- 0.12 vs 2.63 +/- 0.11 mg/Kg x min p less than 0.01) were significantly reduced in patients with Turner. On the contrary hepatic glucose output was similarly suppressed in both groups of subjects. Doubling the insulin infusion rate, we obtained similar results in patients and controls respectively. So we conclude that in Turner syndrome the insulin resistance state is mainly due to a muscular receptor defect.     

Increased peripheral venous somatostatin concentration and decreased glucagon response to arginine in patients with insulin dependent diabetes mellitus without residual B-cell function. Increased plasma SRIF in IDDM

The glucagon response to insulin hypoglycaemia is frequently reduced in patients with IDDM. In the present study arginine infusion, thought to act directly on the islet cells, was used to stimulate somatostatin (SRIF) and glucagon in IDDM without residual B-cell function. Thirteen IDDM patients' were compared with 13 sex- and age matched normal controls following an arginine infusion. The plasma SRIF concentrations in the 'IDDM group' and normal controls increased from 24.2 +/- 2.5 to 31.1 +/- 3.9 pmol/l (P less than 0.01) and 19.7 +/- 1.7 to 23.9 +/- 3.4 pmol/l respectively after 10 min (P less than 0.01). The plasma glucagon concentrations increased from 27 +/- 4.7 to 176 +/- 23.1 pmol/l (P less than 0.01) and 36 +/- 5.0 to 302 +/- 31.9 pmol/l (P less than 0.01) respectively after 20 min. Thus, in long standing IDDM without residual B-cell function, increased plasma SRIF concentrations are found and the glucagon response to arginine is reduced. The last observation further explains why these patients are especially vulnerable to hypoglycaemia.     

Elevated growth hormone levels and insulin resistance in patients with cirrhosis of the liver

Carbohydrate intolerance is frequently seen in patients with hepatic cirrhosis. To study the role of the counter regulatory hormones, glucagon, cortisol and growth hormone in this disease, these hormones were measured in 11 patients with hepatic cirrhosis and six controls during a 4-hour oral glucose tolerance test (OGTT) and in five normal and cirrhotic subjects during steady-state plasma insulin and glucose concentrations (SSPGI) achieved with the euglycemic clamp technique. Fasting plasma glucose was 103 +/- 4.3 mg/dl in cirrhotics and 88 +/- 3.3 mg/dl in controls (p less than 0.001). Immunoreactive insulin (IRI) was 24.3 microU/ml in cirrhotics and 12.7 +/- 2.2 microU/ml in controls (p less than 0.001); immunoreactive glucagon (IRG) was 263 +/- 30 pg/ml in cirrhotics and 122 +/- 17.5 pg/ml in controls (p less than 0.001); serum growth hormone (GH) was 4.4 +/- 0.9 ng/ml in cirrhotics and 0.5 +/- 0.1 ng/ml in controls (p less than 0.001). During OGTT, the 2-hour glucose concentration was 201 +/- 9.7 mg/dl in cirrhotic subjects and 147 +/- 10.0 mg/dl in controls (p less than 0.001). IRG levels were suppressed by 20% of basal values in patients with cirrhosis, while controls showed 10% suppression after an oral glucose load. At 60 minutes, the serum GH was 14.7 +/- 3.9 ng/ml in cirrhotics and 0.3 +/- 0.1 ng/ml in controls (p less than 0.001). The normal suppressive effect of hyperglycemia on GH secretion in controls was sharply contrasted by a paradoxical elevation of serum GH in the cirrhotic group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduced cardiovascular responsiveness to exercise-induced sympathoadrenergic stimulation in patients with cirrhosis

Cardiovascular responsiveness to sympathoadrenergic activation obtained by muscle exercise in the supine position was evaluated in 22 patients with cirrhosis (11 alcoholic, 11 postnecrotic/cryptogenic; 14 with ascites) and 10 controls of comparable age. Plasma norepinephrine, heart rate, diastolic arterial pressure and cardiac function, as evaluated by systolic time intervals, were monitored. At rest, cirrhotics had higher norepinephrine (154 +/- 19 S.E.M. ng/l) and heart rate (79 +/- 2 beats per min) than controls (71 +/- 3 ng/l, p less than 0.01; 67 +/- 2 beats per min, p less than 0.001), whereas diastolic arterial pressure was similar. Among systolic time intervals, electromechanical systole, pre-ejection period, electromechanical delay and pre-ejection period to left ventricular ejection time ratios were prolonged (p less than 0.05 or less). Exercise led to significant increases in plasma norepinephrine, heart rate and diastolic arterial pressure in both controls and patients. In the latter, however, whereas the increase in norepinephrine was greater (p less than 0.001), those in heart rate and diastolic arterial pressure were less (p less than 0.005). As expected, most systolic time intervals shortened, but the decrease in pre-ejection period (p less than 0.05), isometric contraction time (p less than 0.02) and pre-ejection period to left ventricular ejection time ratio (p = 0.06) was less in patients than in controls. Direct correlations between exercise-induced changes in norepinephrine and both diastolic arterial pressure (r = 0.81; p less than 0.005) and heart rate (r = 0.85; p less than 0.002) were observed in controls, while inverse correlations (r = -0.67, p less than 0.001 and r = -0.44; p less than 0.05) were found in cirrhotics. These results suggest that cardiovascular reactivity to the sympathetic drive is impaired in cirrhotics. The impairment of cardiac contractility may be due to altered electromechanical coupling.     

Metabolic effects of cortisol in man--studies with somatostatin

The metabolic effects of chronic hypercortisolaemia were studied by administration of tetracosactrin-depot, 1 mg I.M. daily for 36-60 hr to normal subjects. Partial insulin and glucagon deficiency were induced at the end of the period by infusion of somatostatin, 100 micrograms/h for 210 min. Tetracosactrin alone induced a three fold rise in basal serum cortisol levels and fasting blood glucose concentration rose from 5.2 +/- 0.2 to 7.2 +/- 0.2 mmole/l (p less than 0.01) with a rise in fasting serum insulin from 5.2 +/- 1.2 to 13.1 +/- 1.9 mU/l (p less than 0.02). Concentrations of the gluconeogenic precursors lactate, pyruvate and alanine were also raised, but non-esterified fatty acid, glycerol and ketone body levels were unchanged. Somatostatin infusion caused a 30%-50% decrease in serum insulin and a 20%-60% decrease in plasma glucagon concentrations both before and after tetracosactrin administration. A similar rise in blood glucose concentration, relative to the saline control, occurred over the period of somatostatin infusion both with and without elevated cortisol levels. However, prior tetracosactrin administration caused a 100% greater rise in blood ketone body concentrations during infusion of somatostatin than was seen in the euadrenal state, despite similar plasma NEFA concentrations. Hypercortisolaemia causes hyperglycaemia and elevated gluconeogenic precursor concentrations but the associated rise in serum insulin concentrations limits lipolysis and ketosis. In insulin deficiency, a ketotic effort of glucocorticoid excess is evident which may be independent of lipolysis and occurs despite concurrent glucagon deficiency. These catabolic actions of cortisol are likely to be of major importance in the metabolic response to stress.     

Is somatostatin a humoral regulator of the endocrine pancreas and gastric acid secretion in man?

The effect of low dose infusions of somatostatin on meal stimulated gastric acid secretion was studied in eight healthy volunteers by intragastric titration after a peptone test meal with radioimmunoassay control of the plasma concentrations of somatostatin and the pancreatic hormones glucagon and insulin. Infusion of somatostatin in a dose of 100 ng/kg/h, resulting in a plasma concentration of 13.4 +/- 2.1 pmol/l, inhibited acid secretion significantly, and in a dose of 800 ng/kg/h, with corresponding plasma concentration of 66.5 +/- 12.0 pmol/l the acid secretion was virtually abolished. Plasma concentrations of insulin and pancreatic glucagon decreased significantly during infusion of 200 ng/kg/h (24.5 +/- 7.5 pmol/l) and glucose concentrations increased. Serum gastrin was only significantly decreased during the highest dose of somatostatin. The range of plasma somatostatin concentrations obtained with the lower doses correspond to reported physiological variations. The results support the concept that somatostatin participates in the hormonal control of the pancreatic endocrine and the acid secretion.     

Haemodynamic effects of a long-acting somatostatin analogue in patients with liver cirrhosis

The influence of SMS 201-995 (octreotide, Sandostatin), a long-acting somatostatin analogue, on splanchnic haemodynamics was studied in 15 patients with liver cirrhosis and in 5 healthy individuals before, during, and after 60 min of intravenous SMS infusion (25 and 50 micrograms/h, respectively). No adverse effects of the SMS infusion were seen. In the basal state the estimated hepatic blood flow was 1.04 +/- 0.08 l/min (mean +/- SE) in the patients and 1.62 +/- 0.09 l/min (P less than 0.001) in the controls. At 15 min after the beginning of the infusion the blood flow had already decreased by 15-30% (P less than 0.05-0.01). The reduction was more marked in controls than in patients, and it persisted in both groups during and for 60 min after the infusion. Wedged hepatic venous pressure, measured in the patients, was 20 +/- 2 mmHg in the basal state and 18 +/- 1 mmHg during the infusion (P less than 0.05), and it remained at this level for 60 min after the infusion. Free hepatic venous pressure was unchanged throughout the study. Splanchnic oxygen uptake was similar in the two groups in the basal state and remained unaltered during and after SMS infusion. Both heart rate and arterial systolic and diastolic blood pressure remained unchanged during SMS administration. In summary, SMS infusion results in a fall in hepatic blood flow and a slight but significant decrease in wedged hepatic venous pressure, whereas no effect was noted on the systemic circulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo insulin antagonism but evanescent in vitro tissue effect in rats with growth hormone-secreting tumors

Rats bearing mammosomatotropic tumors have raised insulin but lowered glucose concentrations. To determine if growth hormone (GH) secreted by these tumors causes insulin antagonism, pancreatic suppression tests utilizing infusions (per kg per min) of glucose (8 mg), insulin (200 ng) and somatostatin (1.4 micrograms) for 130 min were performed. Although the steady state plasma glucose and insulin levels (mean of 90, 100, 110, 120 and 130 min samples) were similar in 8 control and 13 tumor-bearing rats, the decrease from the already depressed basal glucose concentration (mmoles/l +/- SE) in the tumor animals was less than in the controls (0.90 +/- 0.30 vs. 2.56 +/- 0.040, p less than 0.005). Since the interpretation of these results was not entirely clear, glucose and insulin-glucose tolerance tests were performed. The glucose disappearance rates (%/min +/- SE) in the glucose tolerance test were lower in 17 tumor rats (2.00 +/- 0.13) compared to 17 control animals (2.51 +/- 0.22). This difference just missed statistical significance (t = 2.00, value of 2.04 necessary for p = 0.05). The decrease occurred in the presence of increased insulin (nmoles/l X 16 min) levels (4.29 +/- 0.38 vs. 2.58 +/- 0.29, p less than 0.005) suggesting insulin antagonism. The glucose disappearance rates (%/min +/- SE) in the insulin-glucose tolerance test were less in 12 tumor-bearing rats compared to 11 control animals (2.80 +/- 0.29 vs. 4.12 +/- 0.35, p less than 0.02). Thus, these GH-secreting tumors cause insulin antagonism in vivo. Freshly isolated hepatocytes from these tumor-bearing animals manifest decreased insulin binding and action (Diabetologia 25:60, 1983). In the present study, however, insulin binding and action (net glucose-C14 incorporation into glycogen) were normal after the hepatocytes were cultured for two days. This suggests that the changes induced by GH in vivo that lead to insulin antagonism are short-lived.     

Inhibition of secretin release and pancreatic bicarbonate secretion by somatostatin infusion in man.

Five healthy students were investigated on two different days with or without a constant infusion of somatostatin (500 microgram/h) into an arm vein a fluoroscopically placed Lagerl?f tube was used for the collection of gastric and duodenal juice. After 30-min basal period, 40 ml 100 mmol/l HCl was infused into the midpart of the duodenum over 5 min through a thin catheter attached to the tube. Plasma immunoreactive secretin was measured by radioimmunoassay employing 125I-labelled synthetic secretin, antibody against synthetic secretin, and standards prepared from pure natural porcine secretin. Secretin levels without somatostatin infusion were 4.6+/-0.7 pmol/l (mean+/-S.E.M.) basally and rose to a peak of 21.8+/-6.2 pmol/l after duodenal acidification (p less than 0.05) and with somatostatin infusion were 4.4+/-0.4 pmol/l basally and rose to a peak of 6.7+/-1.7 pmol/l (n.s.) after duodenal acidification. Pancreatic bicarbonate output increased from 8.0+/-2.5 mumol/min (mean+/-S.E.M.) to 283+/-44 mumol/min without somatostatin infusion (p less than 0.05) and from 6.7+/-2.1 mumol/min to 70+/-13 mumol/min somatostatin (p less than 0.05). This study shows that somatostatin (500 microgram/h can inhibit the release of secretin and the pancreatic bicarbonate secretion after duodenal acidification in man.