The effect of muzolimine on the tubuloglomerular feedback mechanism in the rat kidney.

Inhibition of tubuloglomerular feedback (TGF) by loop diuretics can enhance the diuretic response by attenuating the fall in GFR to be expected with the diuretic-induced rise in distal salt delivery. To establish whether such a mechanism contributes to muzolimine (M)-induced diuresis, TGF activity was tested in male Wistar rats by measuring early proximal flow rate in nephrons, the loops of Henle of which were perfused with M at various concentrations in the presence or absence of M systemically. Since M inhibited TGF only at concentrations far in excess of those adequate to produce substantial diuresis, it is concluded that TGF inhibition by M plays no significant role in the diuretic response to this agent.