Interference with Feedback Control of Glomerular Filtration Rate by Furosemide, Triflocin, and Cyanide

摘要: Microperfusion experiments have shown that increases in flow rate of tubule fluid through the loop Henle are followed by reductions single nephron glomerular filtration (SNGFR) and stop-flow pressure (SFP) measured proximal same nephron. Because changes luminal sodium concentration not consistently related to SNGFR SFP, we explored possibility a transport step at flow-dependent distal-sensing site might be involved feedback control SNGFR. macula densa cells distal adjacent vessels nephrons, they could mechanism. We perfused superficial loops from late early segments three groups rats while measuring SFP nephron, or rates fluid, Na, K, Cl emerging loops. Perfusion solutions used were 0.15 NaCl, Ringer with one several inhibitors electrolyte transport. 10 40 nl/min (also, zero during measurements SNGFR). With alone loop-flow increased nl/min, caused decrease 37.6 32.1 mm Hg, 29.9 18.7 nl/min. Concentrations absorption Na along segment also when perfusion was increased. Decreasing had little effect on The response did occur solution contained furosemide (10(-4) M). No reduction seen other diuretics tested (amiloride, acetazolamide, ethacrynic acid, mercaptomerin) M NaCl alone. reduced furosemide, triflocin, cyanide but amiloride. inhibited cyanide, Amiloride probably do act ascending limb. Ethacrynic acid mercaptomerin known ineffective rat nephrons. Thus, agents interfered