A, recording of the electrical activity of a phasically firing vasopressin neurone showing an increase in the activity induced by microdialysis administration (retrodialysis) of thapsigargin (TG, 200 nm) onto the SON. B and C, changes in activity quotient (B) but not intraburst activity (C) after TG (P < 0.05, n = 6). D, continuously active vasopressin neurones were not affected by thapsigargin. n = 8, Data are means ± s.e.m., *P < 0.05, t tests.