Effects of chronic renal denervation in conscious restrained rats

Abstract

Sodium (Na), calcium (Ca), inorganic phosphate (Pi) and water excretion were measured in nondiuretic (ND) and extracellular fluid (ECF) volume expanded (VE) conscious restrained rats four weeks after denervation or sham-denervation of the left kidney. On the day of the study the animals were lightly anaesthetized with ether and the femoral vessels on one side were catheterized. Urine was collected from both kidneys. The animals were allowed to recover for 3 hours and studied in a restraining chamber. In ND animals isotonic saline containing inulin and para-amino-hippuric acid (PAH) were given at a rate of 0.067 +/- 0.002 (SE) ml/min/kg body weight (BW). In VE animals the infusion rate was 0.24 +/- 0.04 ml/min/kg BW. Kidney catecholamine content was measured after the experiments. Clearances of PAH and of inulin (GFR) were the same in both kidneys. Urine volume (V), sodium excretion (UNa V/GFR), inorganic phosphate excretion (UPi V/GFR) and calcium excretion (UCa V/GFR) were significantly higher in the denervated kidneys. Values in sham denervated kidneys were not greater than those of the right kidney. Denervation was proven by demonstrating absent or very low catecholamine content in the kidneys. The results demonstrate that: chronic renal denervation in rats leads to diuresis and natriuresis even in the conscious state, thus confirming previous results from our laboratory; such changes occur independently of the state of the ECF volume and of renal haemodynamic changes; the increased excretion of Ca++ and Pi after denervation demonstrates that renal nerves affect the reabsorption of these ions either independently or by way of their effect on sodium reabsorption. These data allow us to suggest that a renal tubular dysfunction, which was proved in anaesthetized denervated animals, can also be observed in the conscious state.

Bilateral renal cryodenervation decreases arterial pressure and improves insulin sensitivity in fructose-fed Sprague-Dawley rats

“…Although salt balance was not assessed in the present studies, cryodenervation of renal nerves may also have decreased arterial pressure by attenuating the increase in renal tubular sodium reabsorption reported with fructose feeding and high salt intake (20). Efferent renal sympathetic nerves impinge upon the renal tubular cells (5) and stimulate sodium transport (40,50). Fructose augments renal tubule sodium reabsorption by directly increasing the activity of proximal tubule sodiumhydrogen exchanger 3 and indirectly by sensitizing proximal tubule sodium transport to ANG II (9).…”

Renal denervation modulates angiotensin receptor expression in the renal cortex of rabbits with chronic heart failure

“…In fact, classic studies show that inhibition of adrenergic function by either pharmacological or surgical techniques increases salt and water excretion (5,14). Other studies have shown a natriuretic and diuretic response to chronic renal DnX (51,56), which we believe would be augmented in the HF state.…”

Carl Gottschalk – Physiologist, Bibliophile and Historian of Nephrology

“…Studies later in the 1970s and early 1980s involved the role of the renal nerves in determining sodium and water excretion [46][47][48], showing that the water diuresis in the denervated kidney was accompanied by decrease in sodium reabsorption without any detectable change in glomerular filtration rate (GFR), whilst renal nerve stimulation induced an increase in sodium reabsorption, again without any change in GFR.…”