Tubulo-Glomerular Feedback Activation in Humans before and after Nephrectomy

摘要

Background/Aims: Tubulo-glomerular feedback (TGF) is a key mechanism for controlling glomerular filtration. Nephrectomy for kidney donation provides a good opportunity for studying TGF status before and after a defined loss of renal function. Methods: A total of 22 kidney donors were studied before and one year after nephrectomy. Effective renal plasma flow and glomerular filtration rate were measured by means of para-amino-hippurate and inulin plasma clearances before and after intravenous acetazolamide. Results: TGF activation was not dependent on sex, age or fa-miliality for hypertension either before or after nephrectomy, however, it increased the filtration fraction before, but not after nephrectomy. Nephrectomy did not affect TGF response, but elicited a correlation between TGF response and renal plasma flow, not present in the intact state. Donors with a more activated TGF before nephrectomy had a lower filtration fraction that increased after nephrectomy, while subjects with a less activated TGF before nephrectomy had a higher basal filtration fraction that showed a blunted increase after nephrectomy. Conclusion: TGF is a stable mechanism quantitatively unaltered by nephrectomy, age, sex,menopausal status or family history of hypertension. However, its degree of activation before nephrectomy determines different responses to the loss of a kidney.