1. In anaesthetized cats, reversible nenal nerve denervation (cooling of the renal nerves on one side at 4°C for 16 min) was performed and its effects on haemodynamic and excretory functions of the ipsilateral and the contralateral kidneys were studied.
2. Renal nerve cooling did not cause any change in arterial pressure. Slight increase in blood flow, no change in glomerular filtration rate and a large increase in water and sodium excretion occurred in the ipsilateral kidney; simultaneously, no change in blood flow, a slight and transient decrease in glomerular filtration rate, and a significant decrease in diuresis and natriuresis were observed in the contralateral kidney.
3. Ipsilateral and contralateral renal changes were equally evident in the early (minutes 0 to 8) and late phases (minutes 8 to 16) of the cooling period.
4. When renal nerve cooling was repeated after surgical denervation of the contralateral kidney all contralateral effects were abolished.