Thoracoscopy: general overview and place in the diagnosis and management of pleural effusion

Norepinephrine (NE) was released from perfused spleens either by nerve stimulation or injection of potassium in phenoxybenzamine-treated and normal cats. Krebs-bicarbonate solution was perfused at a rate of about 7 ml/min at 35°C. Perfusion of the phenoxybenzamine-treated spleens with 2.5 mM Mn++ Krebs9 solution reduced the NE outputs to low levels. Perfusion of the normal spleens, pre-exposed to H3-NE infusion, with 0.8, 2.5 or 5 mM Mn++ Krebs9 solution also significantly reduced the net increases in radioactivity, H3-NE and NE by nerve stimulation. Increasing the Ca++ concentration to 10 mM did not significantly alter the inhibitory effect of Mn++. Mn++ also blocked the spontaneous release of radioactivity from spleen. It is concluded that Mn++ acts as a potent inhibitor of NE release and blocks both the nerve-induced and spontaneous release of NE.