β-adrenergic response. The severely blunted response to the β-adrenergic agonist isoproterenol in muscles from dko mice is significantly ameliorated by NBD treatment. ANOVA (repeated measures) indicated that both the factors isoproterenol and frequency, as well as the interaction between these two factors was significantly different between NBD and vehicle treated groups. Stimulation frequency was 4 Hz, at 37°C. * indicates a difference of P < 0.05 between the two groups.