Release of neurotensin from rat spinal cord in vitro

The release of immunoreactive neurotensin (I-NT) from the dorsal half of the rat spinal cord was studied in vitro. A basal release in the order of 0.03-0.06% per min of tissue content was found. Depolarization with K+ caused a dose-dependent increase, with 60 mM K+ causing a 7.7-fold stimulation of release. This K+-evoked release was strictly calcium-dependent. Veratridine (50 microM) produced a 4.9-fold increase which was inhibited by 0.3 microM tetrodotoxin. Noradrenaline, 5-hydroxytryptamine, glutamate, kainic acid, N-methyl-D-aspartate, or quisqualate did not stimulate release of I-NT. The results support a role of NT as a neurotransmitter or modulator in the spinal cord.