Interstitial pressure during volume expansion at reduced renal artery pressure

Publisher Website
Google Scholar
Abstract
To study the effect of oncotic pressure on the relationship between interstitial pressure and Na excretion in the absence of increased peritubular capillary hydrostatic pressure, renal artery pressure was reduced immediately before the start of volume expansion in dogs. Renal interstitial fluid hydrostatic pressure was obtained from chronically implanted polyethylene matrix capsules. Peritubular capillary and interstitial hydrostatic pressures were measured with a servo-nulling apparatus during hydropenia and volume expansion. Oncotic pressure of systemic (.pi.A) and efferent arteriole (.pi.E) plasma was determined. In group 1, reduction of renal artery pressure to 90 mmHg before volume expansion (10% body wt) significantly reduced the rise in interstitial pressure and fractional Na excretion when compared to the contralateral unclamped kidney. In group 2 reduction of renal artery pressure to 75 mmHg before volume expansion prevented increases of interstitial pressure and fractional Na excretion compared to control. Peritubular capillary pressure was significantly decreased. The .pi.E decreased in proportion to the .pi.A. Glomerular filtration rate was not changed in either group at reduced pressure. Reducing renal artery pressure before volume expansion reduces or prevents increases in interstitial pressure and fractional Na excretion. Reduced systemic and efferent oncotic pressure, in the absence of increased peritubular capillary and interstitial pressure, is not associated with natriuresis.

This publication has 0 references indexed in Scilit: