EFFECT OF RENAL AND ADRENAL DENERVATION ON THE RENIN RESPONSE TO SLOW HAEMORRHAGE IN DOGS

SUMMARY 1. The effect on plasma renin activity of moderate slow haemorrhage (7.5 ml. kg⁻¹. h⁻¹ for 2 h) was studied in intact dogs and in dogs whose adrenals and kidneys had been denervated surgically.
2. In dogs with intact renal and adrenal nerves, plasma renin activity rose during haemorrhage without any accompanying change in systemic blood pressure, but with marked decreases in renal function, an increased filtration fraction and an increased haematocrit. The latter effects can be attributed to sympathetic stimulation evoked by haemorrhage.
3. In dogs with denervated kidneys and adrenals, haemorrhage did not result in a significant elevation of plasma renin activity until the 2 h collection period, at which time mean systemic blood pressure had fallen 32 mmHg. Renal function changes were less marked and neither filtration fraction nor haematocrit rose, suggesting the absence of sympathetic stimulation.
4. It concluded that the sympathetic nervous system plays an important role in the renin response to slow haemorrhage until such time as blood pressure falls sufficiently to activate a second stimulatory mechanism, perhaps a renal baro-receptor.