Effects of a bicyclic thymoleptic drug (LU 3–010) on neuroerfector function in rat isolated portal veins

Abstract

The effects of the thymoleptic drug, LU 3–010, on adrenergic transmitter release and reuptake and on effector cell function in rat isolated portal veins have been investigated. The contractile response to exogenous noradrenaline was potentiated by LU 3–010 and its concentration-effect curves after LU 3–010 10−7 g/ml were displaced to the left to a similar extent as had been found in chronically denervated preparations, indicating efficient blockade of the membrane pump mechanism. LU 3–010 10−7g/ml slightly potentiated the neurogenic response to electrical field stimulation, whereas 10−6 g/ml or more reduced the neural effector response in a concentration- dependent manner. The output of radioactive material per nerve impulse after incubation with 3H-NA was also studied. At 10−7 and 3 × 10−7 g/ml of LU 3–010 no significant change in transmitter overflow was observed. At 10−6 g/ml there was a decrease in the “fractional release”, suggesting that LU 3–010 concentrations of 10−6 g/ml or higher reduce transmitter release. Evidence is also given for a direct inhibitory effect of LU 3–010 on the smooth muscle.