The Isolated Perfused Hindquarter of the Rat as a Model for Studying Muscle MetabolismSummary. 1. A detailed description is given of the perfusion technique of the rat hindquarter with a semisynthetie medium. 2. The concentrations of creatine phosphate, ATP and ADP in the muscle tissue after 60--180 min of perfusion were identical with those measured in vivo.3. The glucose uptake of the resting hindquarter of male fed rats was 175.2 tzMol per 30 g/hr 63% of the oxygen consumption accounted for glucose oxidation. No lactate was released to the medium during the first hour of perfusion.4. Insulin (1 mU/ml) caused a 4-fold increase of the glucose uptake, a 7-fold accretion of the muscle glycogen and a 2~-fold increase of the supposed oxydized part of glucose.5. The perfusion of the isolated hindquarter of the rat proved as an appropriate model for the study of skeletal muscle metabolism.Key words: Perfusion of the hindquarter of the rat --Skeletal muscle --Carbohydrate metabolism. Zusammen/assung. 1. Es wird eine ausffihrliche Beschreibung dcr Methode derHinterbeinperfusion mit einem semisynthetischen Medium an der Ratte mitgeteilt.2. Des Phosphorylierungspotential des fiber 60 bis 180 rain perfundiertenMuskelgewebes war mit dem in rive gemessenen identisch. Des elektronenoptische Bild zeigte im Verlauf der Perfusion fiber 60 rain keine VerEnderung der Strukturen. 3. Die Glueoseaufnahme des ruhenden Muskels niehtgehungerter m~nnlieher Ratten betrug 175,2 fzMol/30 g/St& 63% des aufgenommenen Sauerstoffes wurden ffir die Oxydation der Glucose verbraucht. Eine Lactatabgabe an des Medium war w~hrend der Perfusion fiber 60 rain nicht zu beobachten.4. Insulin (1 mE/ml) bewirkte einen 4fachen Anstieg der Glucoseaufnahme, eine Glykogenzun~hme um des Siebenfaehe sowie eine Steigerung des vermutlich oxydierten Glucoseanteiles um des 2~faehe. Die Glycerinabgabe wurde um die ItElfte reduziert, ebenso die Konzentration yon Alanin im Medium.

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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.

1. 2 h after a single oral dose of 25 mg of buformin per normal rat, the blood glucose level was significantly lower when compared to the control group (78,9 4-1.4 rag/100 ml to 67.1 4-5.2 rag/100 ml, p < 0.05). The incubated diaphragms of these animals showed no differences with regard to glucose uptake, lactate produetion and glucose oxidation in comparison to the control.-2. When treated for 7 days with identical dosages of buformin the blood glucose level of the treated rats was lowered to a greater extent (80.5 4-3.7 rag/100 ml to 51.6 4-5.7 rag/100 ml, p < 0.01) and the incubated diaphragms showed a significantly increased glucose uptake, lactate production and decreased glucose oxidation.-3. As a result of these findings and supported by reports in literature it is suggested that the drug may accumulate in the skeletal muscle of normal rats.-4. No insulin potentiating effect could be detected.-5. With regard to previous reported results from our laboratory we suggest that bignanides may increase Cori cycle activity in the rat. tigung kiirzlich yon uns mitgeteilter Bcfunde aus in vivo-Untersuchungen an normalen l~atten, die ergaben, dal~ nach mehrt~giger oraler Vorbchandlung mit 25 mg Buformln der Einbau yon Radioglueose in das Zwerchfellglykogen und der Glykogengehalt selbst erh6ht waren, erschcint es mSglich, dab Biguanide im Skeletmuskel normaler I~atten die Aktivitiit des Cori Cyelus stimulieren.