Exaggerated natriuresis in the hypertensive man: clinical evidence for intrarenal hemodynamic heterogeneity.
7 hypertensive patients (H) and 8 normotensive volunteers (N) were loaded with NaCl (4.5 mEq Na +/kg body weight i.v.) during water diuresis (A) and antidiuresis (B). In 6 antidiuretic subjects (3H and 3N) urine volume (V) was progressively raised up to over 30 ml/min, by intravenous infusion (12 ml/min) of hypertonic (3%) saline (C). It is assumed that in (A) CH2O is an index of Na+ reabsorption in short Henle's loops. In (B) and (C) TcH2O is proportional to Na+ reabsorption in long Henle's loops. In (A) CcH2O was significantly lower in H. In (B) TcH2O was similar in H and N. In (C), TcH2O reached an earlier plateau in H than in N. These results demonstrate that exaggerated natriuresis depends on defective Na+ reabsorption in Henle's loops, suggesting that the defect depends upon the transmission of hypertension to medullary circulation. The increase in hemodynamic pressure in vasa recta opposes Na+ reabsorption both in short and in long Henle's loops. However, the effects on TcH2O of the decrease in Na+ reabsorption in long loops is blunted by the greater Na+ delivery, secondary to the increase in GFR, that follows the rise in filtration pressure.
D000328:Adult; D004231:Diuresis; D005919:Glomerular Filtration Rate; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000503:physiopathology* / Q000652:urine; D008138:Loop of Henle / Q000033:anatomy & histology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009318:Natriuresis; D009399:Nephrons / Q000033:anatomy & histology / Q000098:blood supply / Q000503:physiopathology*; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage; D014563:Urodynamics
D012462:Saline Solution, Hypertonic