Intestinal CART is a regulator of GIP and GLP-1 secretion and expression.

Impaired incretin effect is a culprit in Type 2 Diabetes. Cocaine- and amphetamine-regulated transcript (CART) is a regulatory peptide controlling pancreatic islet hormone secretion and beta-cell survival. Here we studied the potential expression of CART in enteroendocrine cells and examined the role of CART as a regulator of incretin secretion and expression. CART expression was found in glucose-dependent insulinotropic polypeptide (GIP)-producing K-cells and glucagon-like peptide-1 (GLP-1)-producing L-cells in human duodenum and jejunum and circulating CART levels were increased 60 min after a meal in humans. CART expression was increased by fatty acids and GIP, but unaffected by glucose in GLUTag and STC-1 cells. Exogenous CART had no effect on GIP and GLP-1 expression and secretion in GLUTag or STC-1 cells, but siRNA-mediated silencing of CART reduced GLP-1 expression and secretion. Furthermore, acute intravenous administration of CART increased GIP and GLP-1 secretion during an oral glucose-tolerance test in mice. We conclude that CART is a novel constituent of human K- and L-cells with stimulatory actions on incretin secretion and that interfering with the CART system may be a therapeutic avenue for T2D.

Survival and prognostic factors in patients with small bowel carcinoid tumour.

BACKGROUND: Previous studies of small bowel carcinoid tumours usually presented overall or relative survival. This study, in addition, evaluated disease-specific survival in a cohort of patients in a geographically defined population. METHODS: Patients diagnosed with carcinoid of the jejunum or ileum in Jönköping County between 1960 and 2005 were eligible for inclusion. Available tumour specimens were re-examined to confirm the diagnosis. Medical records and pathology reports were reviewed in detail. RESULTS: A total of 145 patients were included in the study. One hundred and thirty-five patients underwent surgery in connection with the diagnosis. Resection was considered complete (R0) in 74 patients (54·8 per cent). Only two localized tumours recurred, whereas no patient with distant metastases was cured. Patients with regional metastases who underwent R0 resection had a better survival than patients with incomplete resection (P = 0·005), and a majority of patients remained recurrence-free. Median overall survival was 7·2 years and median disease-specific survival 12·3 years. In multivariable analysis, age 61-74 years (hazard ratio (HR) 3·78, 95 per cent confidence interval 1·86 to 7·68), age 75 years or more (HR 3·96, 1·79 to 8·74), distant metastases (HR 14·44, 1·59 to 131·36) and incomplete tumour resection (HR 2·71, 1·11 to 6·61) were associated with worse disease-specific survival. Later time period of diagnosis (HR 0·45, 0·24 to 0·84) was associated with better disease-specific survival. CONCLUSION: Age, disease stage and complete resection were identified as independent prognostic factors for survival in patients with small bowel carcinoid tumours. The importance of achieving R0 resection is therefore emphasized.

Neuroendocrine cells in pancreatic duct adenocarcinoma: an immunohistochemical study.

Pancreatic ductal adenocarcinomas can display disseminated neuroendocrine (NE) cells. Controversies exist as to their relative incidence, histogenesis, hormone production, and the prognostic implications of their presence. These issues were elucidated by means of a broad immunohistochemical (IHC) investigation of the resected specimens from 47 patients. Chromogranin A (CgA) was chosen as the major NE marker. In addition, the sensitivity of the conventional IHC procedure was increased by means of the TSA (Tyramide Signal Amplification) technique. In tumours with CgA immunoreactive (IR) cells, detected by the conventional or the TSA methods, these NE cells were further IHC analyzed, using antisera raised against a broad spectrum of neurohormonal peptides, serotonin, and IGF-1. The IHC observations were correlated with clinical and histopathological data, the nuclear IR for the Ki67 antigen (proliferation) of the neoplastic cells, and their IR against the p53 protein. Distinct CgA IR cells were found in 5 out of 47 (11%) tumours when studied by the conventional method, and in 9 out of 47 (19%) when examined by the TSA technique. Corresponding figures, if tumours with only questionable IR against CgA were also included, were 14 (30%) and 23 (50%), respectively. Out of the 9 cases with unequivocal CgA IR, only 3 displayed an IR to an additional hormone or growth factor; this hormone turned out to be somatostatin (only minimal foci). Insulin and glucagon cells also appeared exceptionally. The NE differentiation was found to be unrelated to proliferation, p53 protein expression, and to the survival of the patients. It occurred mainly (7 out of 9) in poorly differentiated adenocarcinomas. Thus, the plain NE immunoprofile of the CgA IR cells, together with the increased IR observed when the TSA technique was used, indicates that the NE cells in these adenocarcinomas are only poorly differentiated. When the CgA IR cells exceptionally become highly differentiated, they can express islet hormones. Using strict structural and IHC criteria, a NE differentiation occurs in less than 20 % of cases; its clinico-pathological significance seems to be non relevant.

Clinical significance of elevated serum chromogranin A levels.

BACKGROUND: Chromogranin A (CgA) has been shown to be a useful marker in the diagnosis of neuroendocrine (NE) tumours. The clinical significance of CgA has been studied mostly in patients with known NE tumours. The diagnosis was evaluated in 153 consecutive patients in whom CgA was measured in a given time interval. METHODS: CgA in serum was measured by radioimmunoassay. Immunohistochemistry with an antibody against CgA was performed in tumours from patients with adenocarcinoma and elevated CgA levels using a conventional method and the more sensitive tyramide signal amplification (TSA) technique. RESULTS: Elevated serum CgA levels were found in 44 patients; 19 had NE tumours and 6 had tumours classified as adenocarcinomas. With the TSA technique, a high proportion of CgA-positive cells were disclosed in five of the adenocarcinoma patients. Patients with atrophic gastritis (no. 2) and patients treated with inhibitors of gastric acid secretion (no. 6) also had elevated levels of CgA. A modest increase in CgA levels was observed in 2 patients with renal impairment, and in 9 patients without any obvious cause. CONCLUSION: The current study confirms that serum CgA is a sensitive marker for the detection of NE neoplasia. Elevated levels found in patients with adenocarcinoma may indicate NE differentiation in the tumour. CgA is a useful tool in the monitoring of enterochromaffin-like (ECL) hyperplasia secondary to treatment with acid secretion inhibitors or atrophic gastritis.

Treatment of ECL cell carcinoids with octreotide LAR.

BACKGROUND: Patients with chronic atrophic gastritis (CAG) and hypergastrinaemia are at risk of developing hyperplasia of the enterochromaffin-like (ECL) cells and ECL-cell-derived tumours. The effect of the somatostatin analogue octreotide on ECL cell carcinoids is examined. METHODS: Five patients with hypergastrinaemia and ECL cell carcinoids were enrolled in a 1-year study of octreotide LAR (long-acting release) 20 mg given at monthly intervals. Biopsies from tumours and from flat oxyntic mucosa were done at the start and 3, 6 and 12 months thereafter. Sections were stained with haematoxylin-erythrosin, immunostained with chromogranin A (CgA) and doublestained with CgA and Ki-67. Serum gastrin and CgA were measured. RESULTS: The number of visible tumours was reduced by more than 50 %. Sections from both tumours and flat mucosa showed a reduced number of CgA immunoreactive cells. Mean serum gastrin decreased from 421 to 186 pM (normal <40 pM); P > 0.05, and serum CgA from 73 to 25 ng/ml (normal < 30 ng/ml); P < 0.001. CONCLUSIONS: During treatment the patients were still markedly hypergastrinaemic, whereas the serum CgA showed normalization. A diminished tumour load and reduced ECL cell density were found, indicating an antiproliferative effect of octreotide directly on the ECL cells.

Openers of ATP-dependent K+-channels protect against a signal-transduction-linked and not freely reversible defect of insulin secretion in a rat islet transplantation model of Type 2 diabetes.

AIMS/HYPOTHESIS: We tested whether chronic overstimulation by levels of hyperglycaemia commonly found in Type 2 diabetes can irreversibly desensitise beta cells and, if so, whether desensitisation relates to the reduction of insulin content and/or the number of beta cells. METHODS: We transplanted islets from Wistar-Furth rats under the kidney capsule to neonatally streptozotocinised recipients. Recipients received daily vehicle, diazoxide (100 mg/kg) or the selective activator of beta cell type K(+)-ATP channels 6-chloro -3-(1-methylcyclopropyl) amino-4 H-thienol [3,2-e]-1,2,4-thiadiazine 1,1-dioxide (NN414) (3 mg/kg) intragastrically for at least 9 weeks. Endpoint measurements were made exactly 7 days after cessation of treatment. RESULTS: Blood glucose did not differ between groups (mean of total: 13.2+/-1.4 mmol/l). C-peptide levels were significantly depressed in drug- versus vehicle-treated rats 3 to 4 hours after the last gastric tubing event, but not at endpoint. Insulin responses to 27 mmol/l glucose from perifused grafts were not significant after vehicle (median increment 18 x 10(-3) microU.islet(-1).min(-1)) but were significant per se and versus vehicle in the diazoxide and NN414 groups (median 107 and 83 x 10(-3) respectively). Rising second-phase secretion was seen only in the drug-treated groups. Stimulation by 25 mmol/l KCl, together with 0.5 mmol/l 3-isobutyl-1-methylxanthine and 3.3 mmol/l glucose, was enhanced in the drug-treated groups (p<0.05 versus vehicle). Graft insulin content did not differ between groups, nor did percentage of beta cells (between 67 and 68% of endocrine cells). CONCLUSIONS/INTERPRETATION: Chronic overstimulation by moderate hyperglycaemia damages signalling events including those required for glucose-induced insulin secretion. This signal transduction defect occurs in the absence of any effect on islet macro-morphometry or insulin stores.

IGF-I in human breast cancer: low differentiation stage is associated with decreased IGF-I content.

OBJECTIVE: Few investigations on the potential role of IGF-I in human breast cancer have used morphological criteria, and the data presented on the localisation of IGF-I are controversial. Moreover, little information exists on a potential correlation between local IGF-I and the grade of malignancy or prognostic factors. Therefore, we investigated the immunohistochemical localisation of IGF-I in specimens of human breast cancer tumours of the ductal type, graded as G1/G2 (well-/moderately differentiated, n=115) and G3 (poorly differentiated, n=28). METHODS: IGF-I immunoreactivity was quantified using a scaling from no (-) to numerous (+++) IGF-I-immunoreactive cells. From 29 of the G1/G2 and 17 of the G3 tumours IGF-I was also measured by RIA. Cytosolic oestrogen receptor (ER) and progesterone receptor (PR) levels, and S-phase fraction were established and related to the number of IGF-I-immunoreactive cells. RESULTS: IGF-I immunoreactivity occurred predominantly in ductal epithelial cells. Of G3 tumours, 57% exhibited IGF-I immunoreactivity as compared with 84% of G1/G2 tumours. Correspondingly, the amount of IGF-I measured by RIA was significantly lower in G3 tumours (6.9+/-0.9 ng/g wet weight) than in G1/G2 tumours (10.5+/-1.1 ng/g wet weight) (P=0.031). G1/G2 tumours exhibited a higher percentage of IGF-I-immunoreactive cells (16% -, 23% +, 41% ++, 20% +++) than G3 tumours (43% -, 37% +, 12% ++, 8% +++). When comparing the - with the +++ G1/G2 tumours, the frequency of IGF-I-immunoreactive cells was related significantly to the ER (P<0.016) and the PR (P<0.008) levels. In G1/G2 and G3 tumours, the ER and PR levels increased with the amount of IGF immunoreactivity while the S-phase fraction increased with decreasing IGF-I content. In 25% of the specimens, IGF-I immunoreactivity occurred in stromal cells, but there was no obvious difference between the different types of tumours. The survival of the G1/G2 tumour patients increased with increasing numbers of IGF-I-immunoreactive cells. CONCLUSIONS: It is concluded that IGF-I is associated with the more-differentiated type of epithelial cells and that increasing dedifferentiation goes along with decreased IGF-I content. Thus, the presence of IGF-I immunoreactivity in breast cancer epithelial cells indicates a lower degree of malignancy than the lack of IGF-I.

Insulin-like growth factor-II in endocrine pancreatic tumours. Immunohistochemical, biochemical and in situ hybridization findings.

In earlier studies a high-molecular-weight (HMW) insulin-like growth factor-II (IGF-II) peptide was identified in adult human pancreas and localized to the insulin-producing B-cells. This peptide has now been investigated in neoplastic insulin cells. Forty endocrine pancreatic tumours and 17 pancreatic adenocarcinomas of ductal type were included in the study. All cases were investigated with immunohistochemical techniques using antibodies to IGF-II, insulin, pro-insulin, glucagon, somatostatin, pancreatic polypeptide, gastrin and vasoactive intestinal peptide (VIP). Frozen tissue from nine tumours and two normal pancreatic glands was extracted, gel separated, and quantified using radioimmunoassay. The tumours were also investigated by in situ hybridization. IGF-II-immunoreactive cells were found in nearly all the 18 insulin-producing tumours (16/18), in a minority of the other endocrine tumours, but not in pancreatic adenocarcinomas. All extracts from the endocrine tumours showed varying amounts of IGF-II and had different molecular-weight forms. The immunohistochemical and radioimmunoassay findings are both based on immunological binding and were further confirmed by Northern blot and in situ hybridization. These results show that IGF-II is expressed in insulin-producing tumours as well as in pancreatic tumours producing other peptides, in contrast to normal pancreatic islets where IGF-II is found exclusively in insulin-producing cells.

Mast cells are involved in the gastric hyperemic response to acid back diffusion via release of histamine.

Acid back diffusion into the rat stomach mucosa leads to gastric vasodilation. We hypothesized that histamine, if released from the rat mucosa under such conditions, is mast cell derived and involved in the vasodilator response. Gastric blood flow (GBF) and luminal histamine were measured in an ex vivo chamber. Venous histamine was measured from totally isolated stomachs. Mucosal mast cells (MMC), submucosal connective tissue mast cells (CTMC), and chromogranin A-immunoreactive cells (CgA IR) were assessed morphometrically. After mucosal exposure to 1.5 M NaCl, the mucosa was subjected to saline at pH 5.5 (control) or pH 1.0 (H(+) back diffusion) for 60 min. H(+) back diffusion evoked a marked gastric hyperemia, increase of luminal and venous histamine, and decreased numbers of MMC and CTMC. CgA IR cells were not influenced. Depletion of mast cells with dexamethasone abolished (and stabilization of mast cells with ketotifen attenuated) both hyperemia and histamine release in response to H(+) back diffusion. GBF responses to H(+) back diffusion were attenuated by H(1) and abolished by H(3) but not H(2) receptor blockers. Our data conform to the idea that mast cells are involved in the gastric hyperemic response to acid back diffusion via release of histamine.

Pattern of distribution and prognostic value of angiogenesis in pancreatic duct carcinoma: a semiquantitative immunohistochemical study of 45 patients.

In specimens obtained from resected pancreata, the intratumoral microvessel density (IMD), the proliferation rate of the neoplastic parenchymal cells, and their p53 protein expression were assessed. The sources of errors were great in the measurements of the IMD. This statement can be illustrated by the finding that when the IMD was calculated by manual counting in five areas of intense neovascularization (hot spot regions), using x200 and x400 magnifications, the numbers of microvessels per square millimeter were 65+/-23 and 106+/-8, respectively, which reflects a significant difference. Two patterns of microvessel distribution could be identified: one with hot spots only in the stroma (n = 19) and one in which the hot spots were located in areas of neoplastic parenchyma (including its stroma) (n = 26). The IMD was significantly greater in the latter group. There was no general correlation of neoplastic disease with the IMD. However, when a scoring system was used to assess the angiogenesis, hot spots in areas of neoplastic parenchyma were associated with a greater proliferation rate of the tumor cells, and with a short length of survival of the patients from their neoplastic disease.

Neuroendocrine differentiation in bronchial carcinomas of classic squamous-cell type: an immunohistochemical study of 29 cases applying the tyramide signal amplification technique.

With regard to the cellular origin of bronchial squamous-cell carcinomas, there are some clinicopathologic and experimental data indicating a link between neuroendocrine (NE) bronchial tumors and the traditionally non-NE squamous-cell carcinomas. Against this background, 29 consecutively resected bronchial squamous-cell carcinomas were examined immunohistochemically (IHC) by means of the specific NE cell marker chromogranin A (CgA), using not only conventional IHC methods, but also the technique with increased sensitivity, offered by the tyramide signal amplification (TSA) procedure. Whereas none of the 29 tumors displayed CgA immunoreactive (IR) cells using the conventional IHC procedure, 10 were found to display a fine granular CgA IR in the neoplastic parenchymal cells using the TSA technique. This incidence is higher than previously reported. However, the CgA IR cells never formed any majority cell population of the neoplastic parenchyma; when present, most of them occurred as micronodules or larger confluent areas in the peripheral most undifferentiated parts of the carcinomatous sheets. Single CgA IR cells were detected only rarely in the spinocellular or keratinized areas. It can be speculated that the observations conform with the recently proposed hypothesis that there is a reservoir of NE progenitor cells in the bronchial mucosa capable of proliferation.

[Immunohistochemical diagnosis by means of tyramide signal amplification]. / Immunhistokjemisk diagnostikk ved bruk av tyramid-signalamplifikasjon.

Immunohistochemistry is used for in situ detection of proteins in histological slides and is now an important diagnostic tool. Due to several methodological and biological factors, conventional immunohistochemical procedures may sometimes have too low sensitivity, especially for tracing the histogenesis of malignant tumours. A few years ago, an amplification technique was introduced which greatly increased the sensitivity of some of the commonly used immunohistochemical methods. This technique permits the use of primary antibodies in significantly lower concentrations compared with the conventional methods. Alternatively, one can keep the antibody concentration unchanged and use the enhanced sensitivity to detect scarce proteins, which are not visualised by traditional immunohistochemical procedures. We present a brief description of the technique and show some examples of its use in the diagnosis of neuroendocrine carcinomas. Tyramide signal amplification might become an important supplement for the diagnosis and classification of malignant tumours.

Spontaneous ECLomas in cotton rats (Sigmodon hispidus): tumours occurring in hypoacidic/hypergastrinaemic animals with normal parietal cells.

We have identified cotton rats with a high female-predominant occurrence of spontaneous gastric carcinomas localized to the oxyntic mucosa, classified as malignant enterochromaffin-like (ECL) omas. The present study was made to further characterize these ECLomas and surrounding oxyntic mucosa, both morphologically using histochemical and immunohistochemical methods, and for gene expression by northern blot analysis. Among eight female cotton rats, three had an irregularly thickened oxyntic mucosa, increased stomach weight and a high serum gastrin level. Histopathological examination showed adenomatous hyperplasia of the thickened oxyntic mucosa with areas of an invasive neoplastic tumour. Immunohistochemistry, using the general neuroendocrine cell marker chromogranin A (CgA) and the specific ECL cell marker histidine decarboxylase (HDC), showed a considerably increased ECL cell density. These ECL cells displayed active proliferation, with hyperplasia, dysplasia and neoplasia. Parietal cells were not found in the tumour tissue. Parietal cell density was only slightly reduced in the surrounding oxyntic mucosa. The antral mucosa was histopathologically normal with a normal number of gastrin-immunoreactive cells. Likewise, somatostatin-immunoreactive cells did not show any differences in the antral and oxyntic mucosa between rats with pathological and normal oxyntic mucosa. Northern blot analysis revealed increased expression of CgA and HDC mRNA in the thickened oxyntic mucosa, whereas H(+)/K(+) ATPase mRNA was similar in the oxyntic mucosa of those with thickened and normal oxyntic mucosa. Gastrin mRNA in the antral mucosa was high in animals with thickened oxyntic mucosa. Somatostatin mRNA expression was similar in the antral mucosa of control animals and animals with a thickened oxyntic mucosa. We conclude that the spontaneous gastric carcinoma occurring in female cotton rats is an ECLoma developing secondary to hypergastrinaemia due to reduced intragastric pH. The mechanism for reduced acidity is not known, but is not gastric atrophy.

Pre- and postnatal testosterone administration induces proliferative epithelial lesions with neuroendocrine differentiation in the dorsal lobe of the rat prostate.

BACKGROUND: Androgens are implicated in the pathogenesis of prostatic carcinoma. We have elucidated the role of pre- and postnatal testosterone administration in the occurrence of proliferative lesions as well as neuroendocrine (NE) cells in the rat prostatic complex. METHODS: Female rats were given a single dose of 9 mg testosterone enantate i.m. on day 15 of pregnancy; it gave a high testosterone exposure to the fetus in the early organogenetic period of the rat prostatic complex. One group of the male offspring was followed without further testosterone treatment; a second group received testosterone only in the pubertal period; a third group was given testosterone from puberty and throughout life (46 weeks). These groups were compared to parallel groups (1A-1C) of male offspring without a testosterone supplement in pregnancy. RESULTS: The serum testosterone concentrations in the rats receiving testosterone were significantly higher than those of control rats. Histopathologically, the testosterone-induced proliferative lesions, mainly hyperplastic, were almost exclusively located in the dorsal lobe. Chromogranin A-immunoreactive (CgA-IR) cells were rarely found normally, but occurred more often in the proliferative lesions (P < 0.001). CONCLUSIONS: The incidence of proliferative lesions in rats exposed to testosterone only in puberty was comparable to the incidence found in those rats receiving testosterone in puberty and throughout life. This finding may have clinical implications for young athletes, who use testosterone as an anabolic drug. The occurrence of CgA-IR cells increased in proliferative lesions in the dorsal lobe of the rat prostatic complex.

Neuroendocrine (ECL cell) differentiation of spontaneous gastric carcinomas of cotton rats (Sigmodon hispidus).

BACKGROUND AND PURPOSE: Female inbred cotton rats develop adenocarcinomas in the oxyntic mucosa. Since a female preponderance is typical for enterochromaffin-like (ECL) cell tumors, we examined such tumors for ECL cells. Gastrin plays a decisive role in ECL cell tumorigenesis, so blood gastrin concentration and gastric mucosal pH were measured. METHODS: The stomachs from six female cotton rats (6 to 8 months old) were studied histologically, and at euthanasia, gastric mucosal pH was determined. Euthanasia was performed on 15 other female cotton rats of similar age for determination of blood gastrin values by radioimmunoassay (RIA) and gastric mucosal pH. Rats were classified macroscopically to have normal or thick oxyntic mucosa, with or without tumor. RESULTS: Among the six cotton rats studied histologically, two 6-month-old rats had normal and two others had thick gastric mucosa, whereas two 8-month-old rats had thick mucosa with tumors. The ECL cells were markedly hyperplastic in all rats with thick mucosa, and ECL cells were found in the neoplastic parenchyma. All cotton rats with normal-appearing gastric mucosa had pH <2.5, whereas 14 rats with thick mucosa had pH >3.1 and hypergastrinemia. CONCLUSIONS: Gastrin may play a major role in ECL cell hyperplasia and, perhaps, in adenocarcinoma genesis.

Clinical and histopathological tumour progression in ECL cell carcinoids ("ECLomas").

AIMS: The aims of this study were to illustrate the malignant potential of gastric enterochromaffin-like (ECL) cell carcinoids (ECLomas) associated with hypergastrinemia, and the gradual neoplastic progression of such tumours. In addition, we examined whether the tyramide signal amplification (TSA) technique could visualize immunohistochemical (IHC) neuroendocrine (NE) features in the dedifferentiated neoplastic ECL cells which were not detected by conventional methods. METHODS: Conventional histopathological and IHC methods for visualizing ECL cells and cell proliferation were used in addition to the TSA technique. OBSERVATIONS: Our patient was followed for 5 years. During that period, her ECLoma displayed all the signs of classical tumour progression, ultimately with the appearance of metastases in the regional lymph nodes, the liver and the skin. The neoplastic ECL cells became progressively dedifferentiated with an increasing number of Ki-67 immunoreactive (IR) cell nuclei. In addition, there was a substantial decrease in argyrophil and IR NE cells that could be visualized by conventional methods. By applying the TSA technique, however, the number of IR tumour cells increased considerably. CONCLUSIONS: ECLomas secondary to hypergastrinemia should be closely followed for signs of clinical and histopathological tumour progression. Such ECLomas deserve early, active, radical surgical treatment. The TSA technique is a valuable tool for visualizing the characteristic IHC features in dedifferentiated NE cells.

Blood flow to the pancreatic islet parenchyma of the Atlantic hagfish (Myxine glutinosa).

The islet organ of the Atlantic hagfish, a cyclostome, phylogenetically is the most original islet parenchyma. It is well equipped with blood vessels, but lacks nerves. The aim of the present study was to evaluate the relative proportions between regional blood flows in these animals with a microsphere technique and with laser-Doppler flowmetry. As regards the results obtained in the kidneys, gills, and islet organ, the data were essentially the same found using both methods. Approximately 20% of the injected microspheres were found in the kidneys; when corrected for weight, the gill bodies and the islet organ were also found to have the same blood perfusion. The blood flow to the brain and that of the gut and the liver were only approximately 30% and 10%, respectively, of that to the kidney. Topical application of the nitric oxide donor, sodium nitroprusside failed to affect the islet blood flow. Apart from this observation, this non-innervated "primitive" islet parenchyma did not differ from that of the amply innervated mammalian islets with regard to their high basal blood perfusion.