Metabolism of smooth muscle

Abstract

1. Isolated gut muscle contains only about 0.25 per cent. of carbohydrate available for glycolysis. • 2. Isolated gut muscle in presence of oxygen oxidises about 1 mg. carbohydrate per gram per hour. • 3. Isolated gut muscle in presence of glucose produces considerable quantities of lactic acid both under aerobic and anaerobic conditions. The deeper portions of the muscle probably do not obtain an adequate oxygen supply even in oxygenated fluid. Under anaerobic conditions about 2 mg. glucose per gram per hour are glycolysed. • 4. Sodium-iodo-acetate (1:10,000) inhibits glycolysis of glucose in Lockets fluid in contact with the gut muscle. • 5. Periodic electrical stimulation increases the glycolysis by about 12 per cent. • 6. Asphyxial arrest of the mechanical movements of gut muscle is not due to accumulation of acid but to exhaustion of its labile carbohydrate store. • 7. The mechanical experiments confirm the biochemical findings that the gut muscle has only a small reserve of available carbohydrate. • 8. The gut muscle probably utilises a mixed diet of carbohydrate and non -carbohydrate material in aerobiosis. • 9. The activity of the gut muscle is maintained best when it is supplied with both glucose and oxygen. • 10. I.A.A. poisoned gut muscle has a very limited activity under anaerobiosis; this suggests a small phosphagen content