Chen J, Fleming J T
Department of Physiology and Biophysics, School of Medicine, University of Louisville, Kentucky.
Kidney Int. 1993 Oct;44(4):684-91. doi: 10.1038/ki.1993.301.
Sympathetic neural control of afferent and efferent arterioles of inner cortical (juxtamedullary) glomeruli has not been established, in part, because of difficulty accessing these vessels, normally located deep below the kidney surface. In this study we utilized the rat hydronephrotic kidney model to visualize the renal microcirculation and to quantitate the responses of juxtamedullary arterioles to brief (30 sec) renal nerve stimulated (RNS). Juxtamedullary afferent and efferent arterioles constricted in a frequency-dependent fashion to RNS, achieving a maximal constriction of 35% to 8 Hz stimulation. In these same kidneys, outer cortical afferent arterioles also constricted to RNS but outer cortical efferent arterioles did not. Microinjection of norepinephrine (NE) around single outer cortical efferent arterioles (to avoid the constriction of preglomerular vessels) constricted the efferent arterioles. However, the afferent arterioles of the same glomeruli were considerably more responsive to microinjected NE. Thus, the lack of constriction of outer cortical efferent arterioles to RNS may relate, in part, to their low sensitivity to NE, the primary neurotransmitter. These direct observations indicate that the juxtamedullary efferent arterioles are responsive to renal nerve stimulation whereas the outer cortical efferent vessels are not. These results, which should be cautiously extrapolated to normal filtering kidneys, indicate that glomerular hemodynamic changes evoked by the sympathetic nervous system are different for outer cortical and inner cortical glomeruli.
肾内皮质（近髓质）肾小球的传入和传出小动脉的交感神经控制尚未明确，部分原因是难以触及这些通常位于肾表面以下深处的血管。在本研究中，我们利用大鼠肾积水模型来观察肾微循环，并定量近髓质小动脉对短暂（30秒）肾神经刺激（RNS）的反应。近髓质传入和传出小动脉以频率依赖的方式对RNS收缩，在8Hz刺激时达到最大收缩35%。在这些相同的肾脏中，肾外皮质传入小动脉也对RNS收缩，但肾外皮质传出小动脉则不然。在单个肾外皮质传出小动脉周围微量注射去甲肾上腺素（NE）（以避免肾小球前血管收缩）可使传出小动脉收缩。然而，同一肾小球的传入小动脉对微量注射的NE反应明显更强。因此，肾外皮质传出小动脉对RNS缺乏收缩可能部分与其对主要神经递质NE的低敏感性有关。这些直接观察结果表明，近髓质传出小动脉对肾神经刺激有反应，而肾外皮质传出血管则无反应。这些结果（应谨慎外推至正常滤过肾）表明，交感神经系统引起的肾小球血流动力学变化在外皮质和内皮质肾小球中是不同的。
