AIMTo study the effect of volume expansion by 0.9% and 1.8% sodium solution on cardiac-renal reflex activity and the role of cardiac-renal reflex in the regulation of integrated function.

METHODS18 health pentobarbital-anaesthetized rabbits were divided evenly into 2 groups at random, bilateral sino-aortic denervation, intubated via right jugular vein to monitor CVP, left renal nerve separated and ending sectioned to record ERSNA, bilateral ureter intubated to collect urine, right femoral intubated to get blood sample. 15% of whole body blood volume of 0.9% and 1.8% sodium solution were injected via jugular vein 10 ml per minute respectively. The CVP, ERSNA, bilateral urine volume and coefficient of sodium excretion were measured before treated, during treated, one minute, five minutes and ten minutes after treated.

RESULTSVolume expansion by 0.9% and 1.8% sodium solution respectively resulted in the increase of CVP by 64.00% +/- 15.56% and 77.00% +/- 23.74%; the decrease of the frequency of ERSNA by 44.00% +/- 13.64% and 63.00% +/- 12.49%, the average burst time of ERSNA by 37.00% +/- 16.49% and 31.00% +/- 10.69%, the increase of average interval of ERSNA bursts by 60.00% +/- 18.38% and 68.00% +/- 27.04%; the increase of urine volume by 158.00% +/- 28.10% and 640.00% +/- 155.39% in left kidney, 192.00% +/- 32.26% and 1343.00% +/- 429.95% in the right; the increase of coefficient of sodium excretion by 132.00% +/- 35.23% and 376.00% +/- 121.72% in the left, 300.00% +/- 76.99% and 856.00% +/- 261.48% in the right.

CONCLUSIONVolume expansion by different solution stimulate the receptors of cardiopulmonary and regulate the water and sodium excretion of the kidney by the cardiac-renal reflex to modulate the stabilization of blood volume.