Autoregulation of blood flow in the rat kidney.
We present evidence showing that renal blood flow (RBF) in the anesthetized nondiuretic rat can be measured reliably and accurately using a noncannulating flow transducer and an electromagnetic flowmeter. In vitro calibration yielded a linear relationship (r=0.998) between flowmeter output voltage and blood flow rates from 0.2 to 10.3 ml/min. Excellent agreement was observed between simultaneous determinations of RBF by the flowmeter and the PAH clearance technique. Glomerular filtration rate and RBF for a kidney with a flow transducer around its renal artery did not differ significantly from corresponding values for the undisturbed contralateral kidney. The relationship of mean RBF with steady-state variations in perfusion pressure was evaluated in 13 nondiuretic rats. RBF averaged 6 ml/min.g kidney wt at arterial pressures (AP) above 100 mmHg. A high degree of autoregulatory efficiency was observed when mean AP varied between 105 and 145 mmHg. Over this pressure range RBF changed only 3% as changes in intrarenal vascular resistance and AP were directly related (r=0.994). Below 95-105 mmHg RBF decreased in a curvilinear fashion with the concavity toward the pressure axis.
D000618:Aminohippuric Acids / Q000652:urine; D000818:Animals; D001783:Blood Flow Velocity / Q000379:methods; D001794:Blood Pressure; D055590:Electromagnetic Phenomena; D005919:Glomerular Filtration Rate; D007668:Kidney / Q000098:blood supply*; D008297:Male; D010477:Perfusion; D011312:Pressure; D051381:Rats; D012039:Regional Blood Flow; D014159:Transducers; D014655:Vascular Resistance
D000618:Aminohippuric Acids