AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 5 770-R775, Copyright © 1986 by American Physiological Society
Sympathetic nervous system and blood pressure maintenance in the Brattleboro DI rat
J. L. Williams Jr and M. D. Johnson
Experiments were performed to determine the functional role of the
sympathetic nervous system (SNS) in blood pressure regulation in
Brattleboro diabetes insipidus (DI) rats and to determine the effects of
synthetic arginine vasopressin (AVP) on sympathetic function in DI rats.
The experiments were conducted in male age-matched Long-Evans (LE) and DI
rats in the conscious unstressed state. Mean arterial pressure (MAP) and
heart rate were similar in conscious unstressed LE and DI rats, but basal
plasma concentrations of norepinephrine (NE) and epinephrine (E) were
elevated in DI rats compared with LE rats. An intra-arterial bolus
injection of hexamethonium (30 mg/kg) resulted in greater reductions of MAP
in DI rats (-62 +/- 5 mmHg) than in LE rats (-42 +/- 7 mmHg; P less than
0.05). Administration of AVP to DI rats by osmotic minipump reduced plasma
NE concentration in DI rats to a level not different from that in LE rats,
but E concentration remained elevated. AVP administration to DI rats also
reduced the hexamethonium-induced fall in MAP in these animals (-47 +/- 7
mmHg) to a level not different from that in LE rats. We conclude that the
SNS plays a greater role in blood pressure maintenance in conscious DI rats
than in LE rats and that AVP administration can normalize plasma NE
concentration and the contribution of the SNS to blood pressure maintenance
in these animals.
