Intratubular and peritubular capillary hydrostatic and oncotic pressures after chronic renal sympathectomy in the anaesthetized rat.

The possible role of peritubular capillary physical forces in the diuretic-natriuretic effects of chronic renal denervation was investigated in Inactin-anaesthetized nondiuretic control (C) and unilaterally denervated (D) rats. Micropuncture techniques were combined with measurement of intratubular and peritubular capillary hydrostatic pressures and afferent and efferent arteriolar plasma oncotic pressures were determined, as well. Compared to data of C rats and of innervated kidneys, marked denervation diuresis and natriuresis were seen without changes in GFR. Both late proximal and early distal (F/P)In values were significantly lower in D kidneys with similar SNGFR. Afferent (pia) and efferent (pi e) arteriolar oncotic pressures were unchanged by denervation (C-pi a = 23.3 +/- 0.79, pi e = 29.9 +/- 0.87 mm Hg; D-pi a = 23.2 +/- 0.94, pi e = 29.8 +/- 1.04 mm Hg). Proximal intratubular hydrostatic pressure was moderately but significantly higher in D kidneys (C = 11.9 +/- 0.5, D = 13.7 +/- 0.3 mm Hg, P less than 0.01), while peritubular capillary pressures were: efferent arteriole (C = 13.9 +/- 0.5, D = 13.4 +/- 0.6 mm Hg, NS). It is concluded that the tubular effects of chronic renal sympathectomy are not dependent on changes in Starling forces of the peritubular environment.