Experimental studies on the glycogen content and the incorporation of radioglucose into the glycogen of the diaphragm of rats after initial and short term administration of buformin

Abstract

After a short term oral administration of 25 mg buformin per animal (100--125 mg/kg/day) and final intraperitoneal injection of glucose we found a significantly increased content of glycogen in the diaphragm of normal male and female rats together with a higher incorporation of glucose. The latter effect was not observed if the last dose of buformin was given 24 h before the investigation. No effect on glycogen content or glucose incorporation into the glycogen was measurable after daily administration of 2.5 mg buformin per animal for 14 days or a single dose of 25 mg buformin per animal.The present investigation confirms the clinical experience that the effect of biguanides is seen only after some days of treatment.

Effects of buformin on the metabolism of the isolated haemoglobin-free perfused hindlimb of normal rats

“…In recent studies from this laboratory concerning the effect of buformin on muscle metabolism we observed an increased glycogen content and a high rate of radioglucose incorporation into the glycogen of the diaphragm of normal rats in vivo after a long term oral administration of buformin --150--175 mg/kg -- [12]. Similar results were reported with the perfused rat heart [15] and in in vivo experiments [11].…”

The effect of buformin upon blood glucose level of normal rats and carbohydrate metabolism of the isolated rat diaphragm

“…With regard to our previously published results (Strohfeldt et al, 1972) with in viva administration of radioactive glucose; the incorporation into glycogen and the glycogen content of the diaphragms of normal rats following several days pretreatment with buformin (25 mg per day animal orally) showed an increased incorporation of radioglucose together with an increased glycogen content of the diaphragms 2 h after the last dose of the drug. Our in vitro observations suggest that biguanides may increase Cori cycle activity in normal rats.…”

“…In support of this argument it has been questioned, whether or not the oxidation-inhibiting effect of biguanides is related to the hypoglyeemic action of biguanides in vivo (Ungar, 1960). It was reported earlier from our laboratory (Strohfeldt et al, 1972) that buformin caused an increase in the glycogen content of normal rat diaphragms in vivo together with an increased incorporation of radioglucose into glycogen when the ammals were pretreated over a period of 12--14 days (25 mg of buformin per day per animal by stomach tube = 100 --125 mg of buformin/kg).…”