Fig. 3. Densitometric quantification of myocardial mRNA encoding cytokines detected in control hearts, interleukin (IL)-1β, IL-4, and IL-6. Perfusion with hypoxanthine–xanthine oxidase (HX–XO) significantly increased density for all three cytokines by approximately threefold (P < 0.05 vs.  control [Con]). Simultaneous administration of isoproterenol with HX–XO was associated with band densities not significantly different form control. Density values are expressed as fold change from control and relative to the L32  housekeeping gene to correct for loading. Values are mean ± SE for IL-6 in five hearts and IL-1β and IL-4 in three hearts.