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Biomedical subjects

R Luft

Publications and source records attributed to R Luft.

At least 55 records · Page 3Linked to original sources
PubMed1979

Effect of glucose/sulfonylurea interaction on release of insulin, glucagon, and somatostatin from isolated perfused rat pancreas.

The effect of a sulfonylurea, glibenclamide, on the release of insulin, glucagon, and somatostatin was studied in the isolated perfused rat pancreas. At glucose concentrations of 1.1 mM or less, the drug stimulated somatostatin release, whereas glucagon release, after 2-3 min of increase, was markedly inhibited. Insulin release was moderately stimulated, and maximal release occurred relatively late. A moderate glucose load (6.7 mM) inhibited glibenclamide-induced release of somatostatin, whereas the two in combination exerted an additive action on insulin release. Greater glucose loads, which by themselves would stimulate somatostatin release, only marginally suppressed glibenclamide-induced somatostatin release. The insulinogenic effect of these glucose levels was not modified by glibenclamide. Glibenclamide may thus stimulate both the alpha and beta as well as delta cells of the pancreas, depending on glucose concentration. We suggest a paracrine (local) interaction of somatostatin with the alpha and beta cells, which has an important role in the kinetics of insulin and glucagon release induced by sulfonylureas.

Animals↗
PubMed1979

Enkephalin- and somatostatin-like immunoreactivities in human adrenal medulla and pheochromocytoma.

By using the Coons indirect immunofluorescence technique, enkephalin-like immunoreactivity with a granular localization was observed in human adrenal medullary gland cells and pheochromocytomas. In two of the tumors and in a few adrenal gland cells, a somatostatin-like peptide could also be identified. Catecholamine cell types were visualized on adjacent sections with antisera to the synthesizing enzymes dopamine-beta-hydroxylase [DBH; dopamine beta-monooxygenase; 3,4-dihydroxyphenylethylamine, ascorbate: oxygen oxidoreductase (beta-hydroxylating), EC 1.14.17.1] and phenylethanolamine-N-methyltransferase (PNMT; noradrenalin N-methyltransferase; S-adenosyl-L-methionine:phenylethanolamine N-methyltransferase, EC 2.1.1.28). In the normal adrenal medulla more DBH- than PNMT-immunoreactive gland cells were observed. In the adrenal pheochromocytoma both DBH- and PNMT-positive cells were seen, whereas the two extra-adrenal tumors contained only DBH. These findings correlated well with plasma catecholamine measurements. Finally, enkephalin immunoreactive fibers and somatostatin immunoreactive cells were observed in a sympathetic ganglion extirpated together with one of the tumors.

Adrenal Gland Neoplasms↗
PubMed1979

Capillary permeability in healthy males with different insulin response to glucose.

The capillary permeability in human skeletal muscle, expressed as capillary diffusion capacity (CDC) for 51Cr-EDTA, was determined during exercise with a local clearance method in two groups of healthy male subjects: a younger group with a mean age of 30 years and an older one with a mean age of 58 years. The main finding was that, in both age groups, CDC was significantly negatively correlated to the early phase of insulin response to an intravenous glucose load. No correlation was found between CDC and peripheral insulin sensitivity. CDC was significantly higher in the older age group (P less than 0.01) independent of insulin response, blood flow and body weight. These data indicate that subjects with low insulin response to glucose have a higher capillary permeability than high responders, and that muscle capillary permeability increases with age.

Adult↗
PubMed1979

Effect of two sulphonylureas on the dose kinetics of glucose-induced insulin release in normal and diabetic subjects.

The effect of two second generation sulphonylureas, gliquidone and glibenclamide, on insulin secretion has been studied in the basal state and in combination with glucose infusions in normal controls, patients with mild maturity-onset diabetes, and subjects with normal glucose tolerance but low insulin response. When injected intravenously, gliquidone caused rapid elevation of plasma insulin, peaking at 5 min in all groups, while glibenclamide induced a slow rise in insulin. Insulin response was somewhat smaller than normal in diabetics and low insulin responders. In all groups, 25 micrograms/kg glibenclamide and 200 micrograms/kg gliquidone were equipotent in generating an insulin response at the basal state. Equipotent amounts of sulphonylureas were combined with glucose in fusions at three different dose levels. The glucose-insulin dose relationships, established by giving glucose alone, demonstrated curves that were flatter, and shifted to the right of the control in diabetics and low insulin responders, the changes being more marked in the former group. Addition of sulphonylurea induced a left shift in the dose-response relationships in controls and low insulin responders; under these conditions the effect of glibenclamide was more pronounced than that of gliquidone. The dose-response relation for glucose-induced insulin release was completely normalized in low responders when sulphonylureas were added. In the group of mild diabetics, insulin response to glucose was enhanced by sulphonylureas only to a modest extent, the dose-response curves remaining grossly abnormal.

Adult↗
PubMed1978

Somatostatin.

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Acromegaly↗
PubMed1978

Effects of short-time somatostatin infusion on the gastric and intestinal propulsion in humans.

The effect of short-time somatostatin infusion on gastric and intestinal propulsion of an oral glucose load was examined in healthy subjects by means of a multiple indicator dilution technique. The early gastric emptying rate was enhanced by somatostatin, indicating delayed gastric inhibition. After withdrawal of the somatostatin infusion, the late gastric emptying rate was decreased and the intestinal propagation rate markedly slowed. The effect of long-time somatostatin infusion has to be examined to analyse the nature of the events described.

Gastric Emptying↗