Glucose utilization rates are linked to the internal free glucose gradient in the rat tapeworm

Hymenolepis diminuta is able to acquire plasma-borne glucose 3-O-[14C]methylglucose in vivo. Free glucose concentrations estimated for this helminth in vivo are comparable to that of the host intestine. Both in vivo and in vitro examinations indicate that the scolex-neck regions (first quartile) of this tapeworm have the highest glucose content, and an anterior-posterior gradient along the second, third, and fourth quartiles was observed. Substrate concentration was rate affecting for glucose utilization rates (measured as substrate depletion from the medium in vitro). Glucose utilization per minute exceeds glucose content by a factor of more than 5. The half-life of glucose was about 10 sec, emphasizing that sugar metabolism is a very rapid process. In addition, utilization was highest in the first quartile and decreased in succession in the second, third, and fourth quartiles. It is concluded that while the exogenous glucose concentration remains stable, regional differences in glucose utilization rates are linked (R = 0.98; P less than 0.01) to free glucose content in H. diminuta.