Reversal of 6-hydroxydopamine-induced hypotension in Long Evans and diabetes insipidus (Brattleboro) rats.

Brattleboro (diabetes insipidus) rats showed a delayed recovery from 6-hydroxydopamine (6-OHDA) hypotension as compared to Long Evans controls. A slight increase in circulating arginine vasopressin was noted in the 6-OHDA-treated Long Evans rats but no change in circulating oxytocin was apparent in either species. The haematocrit and plasma potassium suggested haemodilution in Long Evans rats following 6-OHDA treatment but no such changes were apparent in similarly treated Brattleboro rats. Since the major difference in Long Evans and Brattleboro rats is the latter's inability to synthesize arginine vasopressin (AVP), it is suggested that AVP may have a role in the restoration of homeostasis following 6-OHDA-induced hypotension. This conclusion is supported by (a) a delayed recovery from hypotension and (b) no change in blood concentration parameters, in the Brattleboro rat.