In vitro regulation of lipogenesis in turkey liver explants

A mechanical tissue chopper was used to obtain liver explants (35-75 mg) from 2-3-week old turkeys to determine both tissue sensitivity and metabolic effects of adrenergic agonists (isoproterenol, propranolol, norepinephrine and phenoxybenzamine). A previously noted catecholamine induced decrease in in vitro lipogenesis in chicken liver explants was also noted in turkey liver explants. Thus, one set of control points for in vitro regulation is under control of the cAMP system. Preincubation of slices (1 hr) with propranolol blocked the inhibition of lipogenesis caused by alpha and beta-adrenergic agonists (arterenol or isoproterenol) during a subsequent 1-hr incubation. Preincubation of slices with either of these agonists decreased lipogenesis even following an extensive washout. Inhibition could be overcome with propranolol, a beta adrenergic antagonist.