Skeletal muscle characteristics and carbohydrate metabolism after glucose loading in hypokalaemic periodic paralysis

A prolonged glucose load was administered to four patients with hypokalaemic periodic paralysis and four healthy control sujbects. Muscle ATP and CP concentrations as well as lactate dehydrogenase, hexokinase and phosphorylase activities were similar in those two groups, but succinate dehydrogenase was approximately 50% higher in the control muscles. Muscles fibre composition was almost identical in the two groups, whereas patients had a higher degree of capillarization. Complete muscle weakness was produced in all patients, accompanied by hypokalaemia. Glucose loading resulted in elevated insulin levels and a minor rise in blood glucose level was seen in the patients compared to the control subjects. Glucose loading decreased hexokinase activity in controls, but increased this in the patients. At similar times, muscle and blood lactate levels and blood pyruvate values were generally higher in the patients over the course of the experiment. Initial glycogen concentrations were higher in patients, but glucose loading did not result in greatly increased glycogen values. These data suggest that patients with hypokalaemic periodic paralysis have an enhanced metabolism of carbohydrates and that insulin seems to be an important factor leading to the onset of muscle weakness.