In vitro uptake and release of noradrenaline in chicken liver slices.

White leghorn chicken of either sex (1.5-2.0 kg, 22-25 weeks old) raised under standard conditions of housing, lighting (12 h day light) feeding and vaccination were used. Birds were sacrificed by decapitation, the liver was quickly removed, and kept in cold Kreb's Henseleit physiological saline solution (PSS). Slices (0.3 mm thick, weighing 150-200 mg) were cut and noradrenaline (NA) and adrenaline (A) were estimated flourometrically by the method of Ansell and Beason (1) after extracting catecholamines in acid butanol as described by Sadavongvivad (7) using internal standard. The slices were preincubated for 15 min with iproniazid (10-4M) and tropolone (10-4M) in 10 ml PSS at 37"C with uniform' shaking and NA (10-4, 10 5 or 10-6M) was added and incubated for 5, 10, 15, 30, 45 or 60 min, rinsed 4 times with cold PSS, blotted dry and immediately transferred to acid butanol for NA estimation. Tissues incubated in amine-free medium served as control. To study the disappearance of NA, slices incubated with NA (W-4M) for 45 min were used. After rinsing with PSS they were reincubated in the amine-free medium as above and NA content was estimated at 5, 15, 30, 45 or 60 min. In similar experiments, slices obtained from birds given reserpine pretreatment (5 mg/kg, im on 2 consecutive days) 24 h before, were also used. In some experiments, either cocaine HCI (a specific uptaker blocker), metanephrine tartarate (a specific uptakes blocker), phenoxybenzamine HCI (non-specific uptake blocker) or a combination of cocaine and metanephrine was addad to the PSS during preincubation phase, each at the concentration of 1O-4M. In such studies, NA (10-4M) was added and incubation time was 45 mill. Volume 31 Number 2