A model for evaluation of the peroral insulin therapy: short-term treatment of alloxan diabetic rats with oral water-in-oil-in-water insulin emulsions

Alloxan diabetic rats with fasting blood glucose levels above 300 mg/100 ml were treated with oral administration of water-in-oil-in-water (W/O/W) insulin emulsions at a dose of 50 U/100 g body weight, three times daily for 10 to 14 days. The course of diabetes was followed by determinations of glucose levels in blood and urine. During treatment with oral W/O/W insulin emulsions, daily excretion of urinary glucose decreased by about 30 to 40% (2 to 3 g/day) in all of the five rats studied, and returned to the pre-treatment levels after the treatment being discontinued. During treatment, a significant reduction in fasting blood glucose levels was observed in 4 out of 5 rats, giving the decrease by 18 to 44%. Quantitative estimates suggested that the effectiveness of 50 U/100 g of oral W/O/W insulin emulsions was comparable to that after intramuscular regular insulin at a dose of 0.5 U/100 g. Although oral W/O/W insulin emulsions are still of low efficiency, these results would indicate that diabetes can be controlled by effective oral insulin preparations.

Short-term treatment of alloxan-diabetic rats with intrajejunal administration of water-in-oil-in-water insulin emulsions

Alloxan-diabetic rats with fasting blood glucose levels above 300 mg./100 ml. were treated with intrajejunal administration of water-in-oil-in-water (W/O/W) insulin emulsions via an indwelling catheter at a dose of either 25 or 50 U./100 gm. body weight, three times daily for five to fourteen days. The course of diabetes was followed by determinations of glucose levels in blood and urine. During treatment a significant reduction in urinary glucose levels was observed in all rats studied. In two rats treated with 25 U./100 gm., fasting blood glucose levels did not change significantly. In four of five rats treated with 50 U./100 gm., W/O/W insulin emulsions significantly lessened hyperglycemia during treatment. Quantitative estimates suggested that the effectiveness of 50 U./100 gm. of intrajejunal W/O/W insulin emulsions was comparable to that after intramuscular regular insulin at doses between 1 and 2 U./100 gm. These results would indicate that diabetes can be controlled by enteral administration of insulin preparations.

Radioselenium pancreozymin-secretin test as a clinical test for pancreatic exocrine function

The appearance of radioselenium in the protein fraction of duodenal aspirates has been studied after an intravenous injection of 75-Se-selenomethionine. The continuous flow of pancreatic juice was stimulated by pancreozymin at 120 minutes and by secretin at 140 minutes. A good distinction between normal subjects and patients with pancreatic disease was obtained by measuring 75-Se-radioactivity in the protein fraction of duodenal aspirates; either cumulative radioactivity during the combined 80-minute post-pancreozymin-secretin period, or maximum 75-Se-specific activity during the postsecretin period was used as an index. The test presented here might be a useful and sufficiently reliable method for detecting abnormal pancreatic exocrine function. This test can be performed along with the conventional pancreozymin-secretin test, serum enzyme response to pancreozymin and secretin, and pancreatic scintiscanning.

Dynamic study of exocrine function of the pancreas in diabetes mellitus with scintigraphy using 75Se-selenomethionine

A dynamic study of scintigraphy of the pancreas using 75Se-selenomethionine in diabetic patients was performed. Patients were selected who complained of abdominal pain or diarrhea or both and whose pancreatic exocrine functions were thought to be disturbed. Selenium-75-selenomethionine (3 muCi/kg body weight) was injected intravenously and radioactivity (cpm) was recorded by a scinticamera for 10 min successively up to 120 min. After 20-30 min the increase of radioactivity in the selected area of the displayed pancreas usually reached a plateau. Pancreozymin (1 Harper unit/kg) and secretin (1 harper unit/kg) were administered intravenously and decrease of radioactivity in the same area was followed for 60 min to examine pancreatic exocrine function. After 75Se-selenomethionine injection, the angle of the initial increase of radioactivity, the height of the plateau, and the reactive decrease of radioactivity after pancreozymin and secretin were analyzed in each case. Radioactivity recorded on data tape was reproduced for each 10-min period on a cathode-ray tube display. Areas of interest were selected for dynamic analyses. To supplement the diagnosis by visual image of a scintigram of the pancreas, the scintigram was quantified in the present study and the dynamic curves of radioactivity in the selected area of the displayed pancreas were studied for a total of 3 hr. Application of the dynamic study of the pancreas scintigraphy and the additional data analyses seemed useful for the early detection of pancreatic exocrine dysfunction in diabetic patients in whom the ordinary laboratory pancreatic exocrine function tests gave uncertain results.

Absorption of insulin from perfused rabbit small intestine in vitro

The intestinal absorption of insulin has been studied in a preparation of isolated rabbit intestine in which artificial plasma is circulated through normal vascular channels. After insulin in doses of 100, 200, and 440 U. was introduced into the intestinal lumen, its appearancein the venous effluent was measured immunologically during perfusion for two hours.

Insulin gradually appeared in the venous effluent and reached a peak fifty to ninety minutes after the perfusion was started. The proportion of insulin absorbed was 6.2 to 9.2 per cent with a dose of 100 U., 5.9 to 15.6 per cent with 200 U., and 8.9 to 15.9 per cent with 440 U. The amount of insulin added significantly correlated with the total amount of insulin absorbed from the intestine. The biologic activity in the fraction absorbed was equivalent to that obtained immunologically. In the venous effluent, insulin component was also identified by the relative mobility similar to crystalline insulin on acrylamide gel electrophoresis.

Although the intestinal absorption in this system does not duplicate physiologic absorption, these results indicate that a considerable portion of insulin can be absorbed from the intestine in a physiologically active form.

Increase in plasma immunoreactive insulin following administration of insulin to the gastrointestinal tract of rabbits

Changes in plasma insulin levels in response to enterai administration of insulin have been studied in rabbits.

Insulin, when administered to the stomach, did not cause hypoglycemia at doses up to 150 U./kg. When insulin at doses over 40 U./kg. was infused to the upper jejunum via an indwelling catheter, there was a slight but significant increase in plasma insulin levels, followed by a significant fall in blood glucose. A considerable increase in plasma insulin was observed when insulin at doses over 20 U./kg. was infused to the Thiry-Velia loop of the jejunum in which no pancreatic secretion entered. With a dose of 100 U./kg., the mean plasma insulin rose promptly to the peak of 241 μU./ml., followed by a severe hypoglycemia.

As judged by hypoglycemie and immunological responses, insulin can be absorbed from the intestine in a physiologically active form, but the fraction absorbed is relatively small.