Blood pressure responses to stimulation of afferent fibres in the renal nerve of the rat

ABSTRACT

Chloralose-anesthetised rats were to investigate the blood pressure (BP) responses to electrical stimulation of afferent fibres in the renal nerve. In these rats, stimulation of the proximal end of the cut renal nerve produced either a rapidly reversed fall in BP (at 3V, 5V and 10V) or an initial fall followed by a rise in BP (at 5V and 10V). Dissection of the nerve into two branches and subsequent stimulation yielded a fall in BP by one branch and a rise by the other branch. Also, stimulation of the renal nerve before and after transection at various levels of the medulla oblongata and the spinal cord produced results which indicated that the fall in BP was a bulbar reflex that was integrated at the obex in the medulary region of the brain, but the rise in BP was a spinal reflex that was integrated at a spinal site caudal to the second cervical segment. It is concluded that,in the rat, there are at least two distinct groups of renal afferent fibres which can mediate blood pressures changes that may represent important renal regulatory reflexes.(AU)