Neurotensin in hypothalamo-hypophyseal portal blood

The control of hypothalamo-hypophyseal neurotensin secretion was studied using a modification of the Worthington-Fink portal sampling technique. Portal concentrations of neurotensin were significantly greater than the concentrations found in peripheral plasma, and HPLC characterisation demonstrated that both portal and peripheral plasma neurotensin were very similar. Two different anaesthetic agents, urethane and althesin, did not differ in the resulting portal concentrations of neurotensin. Electrical stimulation of the median eminence resulted in a very marked increase in portal neurotensin concentration.