Tubuloglomerular feedback (TGF) responses become anomalous in rats fed high-NaCl diet after subtotal nephrectomy (STN), such that stimulating TGF causes single nephron GFR (SNGFR) to increase rather than decrease. Micropuncture experiments were performed to determine whether this anomaly results from heightened nitric oxide response to distal delivery, which is a known mechanism for resetting TGF, or from connecting tubule TGF (cTGF), which is a novel amiloride-inhibitable system for offsetting TGF responses. Micropuncture was done in Wistar Froemter rats fed high-NaCl diet (HS) for 8-10 days after STN or sham nephrectomy. TGF was manipulated by orthograde microper-fusion of Henle's loop with artificial tubular fluid with or without NOS inhibitor, LNMMA, or the cell-impermeant amiloride analog, benzamil. SNGFR was measured by inulin clearance in tubular fluid collections from the late proximal tubule.
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