Renal Tissue Blood Flow Regulation System in Acute Blood Pressure Modulation is Maintained in Elderly Wistar‐Kyoto Rats

Abstract

Back ground: Systemic arterial pressure is maintained by sympathetic vasomotor tone regulated by autonomic nerve system. Therefore, attenuation of systemic arterial pressure causes reduction of peripheral tissue blood flow. On the other hand, renal tissue has specific blood flow regulatory system to maintain constant renal blood flow involving autonomic regulatory system. However, the effect of aging in maintenance of renal tissue blood flow regulatory system was not fully established. In this study, we used elderly Wistar-Kyoto (WKY) rats as an aged normotensive animal model, examined relation between systemic arterial pressure modulation and renal tissue blood flow regulation. Method: Aged WKY rats (56w-80w) and control group (16-24w) were anesthetized with chloralose, the arterial pressure, pulse rate and renal tissue blood flow were measured simultaneously. Results: Arterial pressure modulation by intravenous injection of phenylephrine, sodium nitroprusside and the activation of sympathetic vasomotor neurons in rostral ventrolateral medulla were not effected to renal tissue blood flow neither aged group nor control, although baro-reflex was attenuated in aged group. Conclusion These results suggest that renal tissue blood flow regulatory system was maintained in aged normotensive animals, though baro-receptor dependent systemic arterial pressure regulatory system was attenuated. Therefore, although in aged animals, renal tissue autonomic blood flow regulatory system still play important role.