Altered Renal Cortical and Medullary Blood Flow Distribution by Sympathetic Nervous Activation in Spontaneously Hypertensive Rats

(Pages: 11-14)

Takuzo Hano1,* and Naomi Iwane

1Satellite Clinic for Integrative and Anti-Aging Medicine, Wakayama Medical University.
2Department of Health and Nursing Science, Wakayama Medical University, Wakayama, 641-8510, Japan

Abstract:

Present study was carried out to clarify the effect of renal nerve stimulation on renal cortical and medullary blood flow distribution in spontaneously hypertensive rats (SHR). We used 6- (young) and 16- week old (adult) SHR. Renal nerve surround left renal artery was stimulated electrically by 2, 5, 10 and 15 Hz under the anesthesia of isoflurane. Renal blood flow was measured using laser tissue flow meter using noncontact prove for cortical blood flow and contact glass-fiber needle type of prove for medullary flow. After a series of electrical stimulation, 0.1mg of LNAME was injected and same protocol was repeated. Electrical stimulation caused decrease of blood flow in young and adult WKY. In contrast, blood flow in renal medulla showed no significant changes compared with that in cortex. Young SHR showed decrease of cortical and medullary blood flow by nerve stimulation. In adult SHP, blood flow reduction was similar to young SHR and renal medullary blood flow was more reduced than that in young rats. LNAME augmented the reduction of medullary blood flow by electrical stimulation in WKY and young SHR. In adult SHR, LNAME showed no effects on blood flow reduction in renal medulla. In conclusion, these results showed that medullary blood flow is protected through the nitric oxide production in normotensive rats but this mechanism is blunted in SHR.

Keywords:

Renal blood flow, Renal medulla, Hypertension, Sympathetic nerve.