Gladys Perisutti

Insulinase-inhibitory activity of protein hydrolysates.

Conclusion Destruction of insulin by extracts of rat liver is inhibited competitively by 3-hour acid hydrolysates and by tryptic and chymotryptic digests of a variety of proteins. Insulinase-inhibitory activity is attributed to a peptide (or peptides) which loses activity on complete hydrolysis.

The inhibition of the action of insulin on rat epididymal adipose tissue by sulfhydryl blocking agents

Abstract Concentrations of iodoacetate and N -ethylmaleimide which produce no significant effect on the spontaneous oxidation of glucose by rat epididymal adipose tissue in vitro inhibit the action of insulin. These agents do not inhibit the binding of insulin to adipose tissue or to the isolated diaphragm in vitro .

Ineffectiveness of Sulfonylureas in Alloxan Diabetic Rats.

Summary Oral administration of 100 mg 1-3-butyl-p-tolylsulfonylurea per kg body weight to normal rats results in a marked hypoglycemia within one hour which persists for 4 hours. No significant change occurs in blood sugar of similarly treated alloxan diabetic rats.

THE ROLE OF INSULINASE IN THE HYPOGLYCEMIC RESPONSE TO SULFONYLUREAS

The hypoglycemic response of the healthy animal or man to the administration of a single dose of tolbutamide (Orinase) is divisible into two phases: (1) an initial phase lasting less than one hour, during which a maximum decrease in the blood sugar concentration occurs; and (2) a subsequent phase of restitution, lasting a variable period of time, during which the blood sugar is gradually restored to its initial concentration (FIGURE 1). With an oral dosage of less than 50 mg. tolbutamide per kilogram of body weight, both

Influnce of Insulin on Uptake of Monosaccharides by the isolated Rat Diaphragm

Summary The influence of d-tubocurarine, two central nervous system depressants (pentobarbital and chloral hydrate) and two central nervous system stimulants (pentylenetetrazol and 5-ethyl-5-(1,3 dimethylbutyl) barbituric acid) on the concentrations of inorganic phosphate, phosphocreatine, and ATP in the cerebrum of the rhesus monkey has been investigated. d-Tubocurarine was the only one of these compounds to produce any statistically significant effect. With this agent there was a singnificant decrease in phosphocreatine content without any alteration in inorganic phosphate or ATP.

Destruction of I131 labeled insulin by liver slices.

Summary 1. Insulin labeled with I131 was used to determine the effect of liver slices on the degradation of insulin. 2. The insulin-inactivating activity of slices of rat liver (insulinase) is associated with a degradation of I131 insulin. 3. The degradation of I131 insulin by liver slices follows first order kinetics and is related directly to the quantity of liver slices employed. 4. A non-protein fraction of liver (insulinase-inhibitor) which inhibits the action of insulinase also inhibits the degradation of I131 insulin by liver slices.

Effect of insulinase-inhibitor on destruction of insulin by intact mouse.

Summary A non-protein fraction of liver which can inhibit the destruction of insulin by extracts and slices of liver, is effective also in inhibiting the destruction of exogenous insulin by the intact mouse. This factor, insulinase-inhibitor, appears to act as a competitive inhibitor.

Insulinase-inhibitory action of metabolic derivatives of L-tryptophan.

Conclusions Metabolic derivatives of l-tryptophan which produce a hypoglycemic response in rats are effective also as inhibitors of the destruction of insulin by fresh extracts of rat livers and by intact mice.