[The hypertensive effect of vasopressin administered into the median eminence of the hypothalamus in rats].

Data about direct effect of vasopressin (VP) on the central arterial pressure (AP) orientated us to investigate the effect of its local administration in the median eminence (ME) of the hypothalamus in rats. For this purpose VP was administered in ME under micropellet form. AP was measured indirectly on the tail of rats up to 96th hour after operation. After implantation of VP there was an elevation of AP with maximum in the first hour, which was statistically significant (p less than 0.01). Identical manipulation (sham operation) was performed to control the lesion effect. Transitory lowering of AP with maximum in the first hour was also established and it was statistically significant (p less than 0.001), For exclusion a nonspecific systemic effect of VP the same dose was administered in the parietal cortex, during which transitory and short-lasting reaction occurred in the first hour after the operation. The data indicate that the peptide, administered in ME under micropellet form, could induce a longlasting hypertensive effect.