D.R. Wagner, U.Gresser, N. Zollner
Medizinishe Poliklinik der Universitat Munchen, FRG
Ann Nutr Metab 1991:35:297-302
Abstract. Three patients with AMP deaminase deficiency (AMPD deficiency) performed exercise on a bicycle ergometer with increasing work load \~hout and with administration of ribose (3 g p.o. every l 0 min. beginning l h before exercise until the end). The patients performed exercise until heart rate was 200 minus age. Maximum capacity was not increased by administration of ribose. but postexertional muscle stiffness and cramps disappeared almost completely in 2 of 3 AMPD-deficient patients. Plasma concentrations of lactate and inosine were increased in AMPD-deficient patients after oral administration of ribose. Our data suggest that ribose may both serve as an energy source and enhance the de novo synthesis of purine nucleotides.
AMP deaminase deficiency (AMPD deficiency) is a relatively frequent enzyme defect of skeletal muscle ( 1.5% of muscle biopsies) [ 1]. Clinically, it is characterized by postexertional muscle stiffness and cramps. AMP deaminase (myoadenylate deaminase) is one component of the purine nucleotide cycle. The disruption of the purine nucleotide cycle induced by AMPD deficiency is probably the cause of the muscular disorder. So far, the only successful therapeutic approach has been the oral administration of ribose. The beneficial effect of ribose in AMPD deficiency has only been achieved by high oral doses (3-4 g) administered continuously (every I 0 min) during exercise, as first described by Zollner et al. [2]. Lower and not exercise-related doses of 500 mg ribose 4 times a day were not successful. Besides occasionally occurring diarrhea no side effects have been noted during ribose therapy. The beneficial effect of ribose has mainly been attributed to an additional energy source [2] and possibly also to enhanced de novo synthesis of purine nucleotides [3].