Leonard B L, Navakatikyan M A, Malpas S C
Department of Physiology, University of Auckland Medical School, New Zealand.
Auton Neurosci. 2000 Sep 1;83(1-2):19-28. doi: 10.1016/S0165-1838(00)00103-X.
Renal sympathetic nerve activity (RSNA) and renal blood flow (RBF) both show oscillations at various frequencies but the functional significance and regulation of these oscillations is not well understood. To establish whether the strength of these oscillations is under differential control we measured the frequency spectrum of RSNA and RBF following volume expansion in conscious rabbits. Seven days prior to experiment animals underwent surgery to implant an electrode for recording renal nerve activity and a flow probe for recording RBF. Volume expansion (Haemaccel, 1.5 ml min(-1) kg(-1) for 15 min) resulted in a 25 +/- 5% decrease in mean RSNA, paralleled by an increase in RBF to 60 +/- 12 ml min(-1) from resting levels of 51 +/- 11 ml min(-1). Renal denervated rabbits did not show an increase in RBF with volume expansion. Arterial baroreflexes were unaltered by volume expansion. Spectral analysis of the different frequencies in RSNA showed oscillations in RSNA between 0.2 and 0.4 Hz were selectively decreased following volume expansion (14 +/- 3 to 6 +/- 1% of total power in RSNA at < 3 Hz). A corresponding decrease in the strength of oscillations in RBF at this frequency was also seen (20 +/- 6 to 8 +/- 2%). In contrast, the strength of respiratory (0.8-2.0 Hz) and cardiac (3-6 Hz) related rhythms did not change with volume expansion. These results show that selective changes in the different frequency components of RSNA can occur. We suggest that input from cardiopulmonary receptors and/or other vascular beds, and/or altered vascular resistance after volume expansion can reduce the strength of the 0.3 Hz oscillation independent of changes in arterial baroreflex control of RSNA.
肾交感神经活动（RSNA）和肾血流量（RBF）均呈现出不同频率的振荡，但这些振荡的功能意义和调节机制尚未完全明确。为了确定这些振荡的强度是否受到差异控制，我们测量了清醒家兔容量扩张后RSNA和RBF的频谱。在实验前7天，动物接受手术植入用于记录肾神经活动的电极和用于记录RBF的血流探头。容量扩张（贺斯，1.5 ml min⁻¹ kg⁻¹，持续15分钟）导致平均RSNA下降25±5%，同时RBF从静息水平51±11 ml min⁻¹增加到60±12 ml min⁻¹。去肾神经的家兔在容量扩张时未出现RBF增加。容量扩张未改变动脉压力反射。对RSNA不同频率的频谱分析显示，容量扩张后，RSNA在0.2至0.4 Hz之间的振荡选择性降低（在<3 Hz时，RSNA总功率的14±3%降至6±1%）。在该频率下，RBF振荡强度也相应降低（20±6%降至8±2%）。相比之下，呼吸（0.8 - 2.0 Hz）和心脏（3 - 6 Hz）相关节律的强度在容量扩张后未发生变化。这些结果表明，RSNA不同频率成分可发生选择性变化。我们认为，容量扩张后心肺感受器和/或其他血管床的输入和/或血管阻力改变，可降低0.3 Hz振荡的强度，而与RSNA的动脉压力反射控制变化无关。
