[Glucose transport inhibition in human erythrocytes by calmodulin antagonists]. / Tormozhenie transporta gliukozy v éritrotsitakh cheloveka antagonistami kal'modulina.

Calmodulin antagonists (tryphtazin, lidocaine, dykain, palmitate) inhibit glucose transport from human erythrocytes. Glucose efflux inhibition is proportional to the concentration of antagonists in the medium and is of uncompetitive character. It is accompanied by a decrease in the maximum transport rate with the unchanged constant of dissociation in the complex: carrier-sugar. Calcium ionophores A23187 and divaleryldibenzo-18-crown-6 eliminated the inhibiting effect of pharmacological agents on glucose transport. The authors think that the glucose transport inhibition under the influence of calmodulin antagonists may be realized through the calmodulin-dependent chain inhibition under the influence of calmodulin antagonists in the carbohydrate transport system.

[Protamine sulfate-induced resistance to the hypoglycemic effect of insulin]. / Rezistentnost' k gipoglikemicheskomu deistviiu insulina, vyzvannaia protaminsul'fatom.

Administration of protamine sulfate in a dose (0.9-1.1 mg/200 g) sufficient for binding reactive circulatory heparin provokes in rats the status of temporary resistance to the hypoglycemic action of both exogenous and endogenous insulin. This effect occurs after protamine sulfate administration 5-30 minutes prior to insulin in doses of 0.2-2.4 Units/200 g, respectively, or release of endogenous heparin stimulated by sugar load. As the time interval between administration of protamine sulfate and administration (release) of insulin is prolonged or shortened, the status of resistance does not develop. Protamine sulfate does not produce any effect on the blood concentration of immunoreactive insulin. Similarly to protamine sulfate, the resistance to the hypoglycemic action of insulin may be also provoked by the synthetic heparin antagonist, 2,5-ionene that binds heparin, forming a stable polyelectrolyte complex ionene-heparin. Administration of a sufficient heparin dose (10 Units/200 g) may interrupt the protamine sulfate-induced resistance, which manifests in the recurrence of the hypoglycemic action of insulin. There are reasons to assume that the presence of reactive heparin in the circulation is necessary for insulin reception by target tissues.

Thermal and glycemic responses during mild exercise in +5 to -15 degrees C environments following alcohol ingestion.

Male volunteers (3 groups of 6) were tested once after drinking alcohol (alc) and once after consuming a placebo. The subject drank 2.5 ml of 40% alc/kg in 30 min and, wearing a sweat suit, entered an environmental chamber (+5 degrees, -5 degrees, or -15 degrees C; one group at each temperature). Intermittent, bicycle exercise was performed for 3 h (40% VO2 max, 20 min work--10 min rest repeated 6 times). Peak blood alc (11.87 +/- 0.82 mM/occurred at 87.4 +/- 7.5 min; there were no differences between the three temperature groups. Based on pulmonary VO2 and RQ, neither environmental temperature nor alcohol affected metabolism, but blood glucose was significantly (p less than 0.05) lower with alcohol from 105 min until the end of the 3 h. Mean body temp was lower (p less than 0.05) in the -15 degrees C group and alcohol resulted in lower (p less than 0.05) body temperature in all three groups for the first 2 h. However, subjects did not perceive the increased heat loss or lower body temperatures. In contrast to cold water immersion studies, alcohol ingestion followed by mild exercise in a cold air environment results in enhanced heat loss and lower blood glucose levels.

Combined use of guar and acarbose in reduction of postprandial glycaemia.

Symptoms associated with carbohydrate malabsorption limit the usefulness to diabetics of a powerful glycoside-hydrolase inhibitor (acarbose) which reduces postprandial glycaemia. Addition of a low dose (50 mg) of a acarbose together with 14.5 g guar gum to a breakfast test meal taken by 8 healthy volunteers reduced the mean peak rise in blood-glucose at 30 min by 70%. Areas under the insulin and gastrointestinal-polypeptide response curves were also greatly reduced. No evidence of carbohydrate malabsorption, as assessed by measurement of breath hydrogen, was found during any of the test periods. When acarbose was taken alone, 3 of the 8 subjects had troublesome symptoms and the 30 min rise in blood-glucose was reduced by only 28%. Thus, combination of these two agents effectively reduces the rate of carbohydrate absorption without increasing side-effects and may make combined acarbose and guar acceptable in the management of some diabetics.

[Insulin secretion in rats after hypothalamic damage]. / Sekretsiia insulina u krys posle povrezhdeniia gipotalamusa.

Experiments conducted on female Wistar rats showed that 24 hours after the injury of the ventromedial nuclei of the hypothalamus (VMNH) without animal starvation there occurred a slight reduction of insulin in the islets and a significant elevation of the blood immunoreactive insulin (IRI) level, without any glycemia reduction. In animals with intact VMNH glybenclamide produced no changes in the insulin depot in the pancreatic cells, but somewhat increased the IRI level. However, after the VMNH injury glybenclamide caused a sharp insulin depletion in the islets, and a marked elevation of IRI and a decrease of sugar in the blood.

[Oral administration of insulin with synthetic polymers]. / Oral'noe vvedenie insulina s sinteticheskimi polimerami.

A saccharolytic action of insulin given orally with various synthetic polymers to rabbits was studied. Blood sugar level gave the greatest fall when insulin mixtures with strong electrolytes were used. In this case when the weight proportion of insulin-polymers was 1 : 5 insulin action was prolonged to 5 hours, addition of surfactants permitted to get an analogous saccharolytic effect with reduction of the insulin dose by half (50 AU per animal).

Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol.

To determine the part played by altered gastric emptying in the modification of glucose absorption by gel fibres, glucose tolerance tests were done in seven healthy volunteers with and without the addition of pectin to the ingested glucose solution and after pharmacological inhibition of gastric emptying with propantheline. Compared with the controls, pectin significantly reduced blood-glucose. Propantheline had a similar but more pronounced effect. Pectin and guar gum did not substantially alter glucose tolerance in a patient who had had total gastrectomy. In a further investigation, gastric emptying and paracetamol absorption were studied simultaneously in fourteen subjects. In eight of these the study was repeated after addition of guar gum and pectin to the ingested paracetamol. Both gastric emptying and paracetamol absorption were slower after gel fibre but the total absorption of the drug, reflected in urinary recovery, was not significantly reduced. The results suggest that the effects of guar gum and pectin on glucose tolerance and paracetamol absorption could be due simply to alteration in the rate of gastric emptying.

Sucrose malabsorption in man after ingestion of alpha-glucosidehydrolase inhibitor.

The effect of an alpha-glucosidehydrolase inhibitor (alpha-G.H.I.) on intestinal absorption of sucrose was assessed by measuring rises in blood-glucose and intestinal hydrogen production after ingestion of 100 g sucrose. 200 mg alpha-G.H.I. given with the sucrose completely inhibited early postprandial blood-glucose rises, prevented late postprandial dips in blood-glucose, and considerably increased breath-hydrogen levels, which indicates sucrose malabsorption. Thus the inhibitor can be used to study carbohydrate malabsorption and may be useful as a method for retarding carbohydrate absorption.