Attenuated cardiovascular and sympathetic nerve responses to aortic nerve stimulation in DOCA-salt hypertensive rats

In order to verify, whether baroreflex sensitivity is changed centrally in DOCA-salt hypertension, the left aortic depressor nerve (ADN) was electrically stimulated in DOCA-salt hypertensive rats. After 3 weeks, tail-cuff systolic pressure was significantly higher in DOCA-salt treated rats than in untreated rats (169 +/- 4 versus 130 +/- 4 mmHg, respectively; P less than 0.001). After cutting both ADN and the carotid sinus nerves, the central cut end of the left ADN was electrically stimulated and frequency dependent depressor, bradycardic and sympatho-inhibitory responses were elicited in both control and DOCA-salt hypertensive rats. However, these responses were significantly smaller in DOCA-salt hypertensive rats than in normotensive controls. Bradycardic and sympatho-inhibitory responses to i.v. injection of norepinephrine were also blunted in DOCA-salt hypertensive rats. These findings suggest that baroreflexes were centrally attenuated in DOCA-salt hypertensive rats and possibly contribute to overall baroreflex attenuation.