Diabetic Traits in a Strain of Rats1

Abstract

A a result of an investigation of the effects of drugs on the carbohydrate metabolism of rats, control glucose tolerance tests revealed that pedigreed, sexually mature, male rats of the Yale strain 2 exhibited a significantly lower glucose tolerance than rats of the Wistar strain of corresponding age and sex, grown under the same conditions and maintained on the same diet. In view of the extensive use of rats in carbohydrate studies, considerable importance is attached to the questions, a), Which strain has a 'normal' carbohydrate tolerance? b), What criteria justify the designation 'normal' carbohydrate tolerance in the rat?Relative to these questions, the data here reported cover a period of 22 months and consist of 425 glucose tolerance tests on 240 rats, normal with respect to weight gains and general physical appearance.

The functional significance of a spontaneous pancreatic islet change in aged rats

“…A diminished glucose tolerance in elderly humans [12,2,9,11,14,5] and in rats [3] is shown to occur. Its pathogenesis, however, has not been fully evaluated as relatively few large scale studies have been carried out in the aged to correlate functional response with islet morphology.…”

“…The intra-peritonea] glucose tolerance test was performed, according to the methods used by WEXLER and FISHIER [13], and COLE and HA~NED [3], (350 mg of glucose in a 10 ~o solution per 100 g of body weight, after 18 hours of starvation, 0, 1/2, 1, 2, 3, 5 hour values). The result of the tests was evaluated statistically as well as according to the criteria set by COLE and HAI~NED [3]. The conditions of normal values were as follows: 1.1/2 hour value greater than 1st hour level.…”

Ketohexokinase, isoenzymes of glucokinase and glycogen synthesis from hexoses in neonatal rat liver

“…As the adult isoenzyme develops, the liver gains in ability to synthesize glycogen from glucose (Fig. 3) and the affinity of the enzyme for glucose is such that large variations in the rate of glucose phosphorylation would occur with variations in the concentration of blood glucose over the normal range of about 3-10 mM (Cole & Harned, 1938). The Michaelis constant of adult glucokinase (1-3 x 10-2M) is thus favourable for the operation of a control mechanism based on the Michaelis relation between substrate concentration and velocity of the enzyme reaction.…”

The effect of concentration on glucose phosphorylation and incorporation into glycogen in the livers of foetal and adult rats and sheep

“…The glucokinase present in adult rat liver, but absent in foetal rat liver, has a Michaelis constant for glucose of 10-40 nmN (DiPietro, Sharma & Weinhouse, 1962;Walker, 1962;Ballard & Oliver, 1964). This property would permit enzymic control over the rate of glucose phosphorylation in response to changes in the concentration of blood glucose over the normal range 3-10 mm (Cole & Harned, 1938). This form of glucokinase would thus enable the rat liver to regulate the uptake of glucose from the blood and thus the amount of glycogen stored in the liver.…”