Renal sympathetic nerve activity and renal responses during head-up tilt in conscious dogs.
Renal sympathetic nerve activity (RSNA) was measured in conjunction with functional responses of the kidney during head-up tilt in eight conscious female dogs. A 40 degree head-up tilt resulted in a sustained increase in RSNA by 53 +/- 10% (P less than 0.05) relative to control level. Urine flow and osmolal and sodium excretions decreased significantly to a nadir of -55 +/- 4, -42 +/- 7, and -59 +/- 10%, respectively, whereas free water clearance and creatinine clearance did not change significantly during head-up tilt. The systemic arterial pressure (at kidney level) increased significantly from 110 +/- 4 to 129 +/- 6 mmHg, and central venous pressure decreased significantly from -0.7 +/- 0.5 to -7.6 +/- 0.6 mmHg. The chronic bilateral renal denervation, which was performed 2-4 wk before the experiment, abolished both the antidiuretic and antinatriuretic responses to heald-up tilt. These results indicate that an increase in RSNA plays a significant role in the decrease in urine flow and sodium excretion induced by 40 degree head-up tilt in conscious dogs.
Miki
K
K
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Hayashida
Y
Y
Tajima
F
F
Iwamoto
J
J
Shiraki
K
K
D000818:Animals; D001794:Blood Pressure; D004285:Dogs; D005260:Female; D007668:Kidney / Q000294:innervation / Q000502:physiology*; D009431:Neural Conduction; D011187:Posture; D012964:Sodium / Q000652:urine; D013564:Sympathetic Nervous System / Q000502:physiology*; D014882:Water-Electrolyte Balance
D012964:Sodium