Isoproterenol-Induced Calorigenesis of Dystrophic and Normal Hamsters

Abstract

Summary

The calorigenic response of dystrophic hamsters (showing minimal impairment of locomotion or muscle destruction) to the β-adrenergic agonist, isoproterenol, was significantly lower than that of normal hamsters at the higher concentrations (near 10 μg/kg-min) of the infused catecholamine. That differences between dystrophic and normal hamsters did not occur over the entire concentration range suggests that the altered responsiveness of the myopathic animals cannot be attributed solely to a decreased concentration of active catecholamine at the receptor site, a decreased number of functional receptors and/or a decreased affinity of the receptor for isoproterenol. On the other hand, the lowered calorigenic response of the dystrophic hamsters (which appears to reflect a decrease in their ability to generate heat via nonshivering mechanisms) is consistent with the proposed occurrence of alterations in the metabolic pathways associated with NST in skeletal muscle.