title: Mechanisms of temporal variation in single-nephron blood flow in rats.
abstract: Modified laser-Doppler velocimetry was used to determine the number of different mechanisms regulating single-nephron blood flow. Two oscillations were identified in star vessel blood flow, one at 20-50 mHz and another at 100-200 mHz. Tubuloglomerular feedback (TGF) mediates the slower oscillation, and the faster one is probably myogenic in origin. Acute hypertension increased autospectral power in the 20-50 mHz and 100-200 mHz frequency bands to 282 +/- 50 and 248 +/- 64%, respectively, of control even though mean single-nephron blood flow was autoregulated. Mean blood flow increased 24.6 +/- 6.1% when TGF was inhibited by intratubular perfusion with furosemide, and it decreased 42.8 +/- 3.9% when TGF was saturated by tubular perfusion with artificial tubular fluid at high rates. Autospectral power in the low-frequency band decreased 50.5 +/- 9.6% during furosemide and decreased 74.9 +/- 5.9% during TGF saturation, consistent with a TGF origin of the slow oscillation. In contrast, autospectral power of the high-frequency oscillation increased 75.4 +/- 23.9% during TGF inhibition and decreased 35.8 +/- 11% when TGF was saturated, suggesting interactions between the two spontaneously oscillating components in efferent arteriole blood flow.
authors.affiliation: Department of Physiology and Biophysics, University of Southern California School of Medicine, Los Angeles 90033.
authors.forename: K P
authors.initials: KP
authors.lastname: Yip
authors.forename: N H
authors.initials: NH
authors.lastname: Holstein-Rathlou
authors.forename: D J
authors.initials: DJ
authors.lastname: Marsh
mesh_terms: D000818:Animals; D001160:Arterioles / Q000502:physiology; D001783:Blood Flow Velocity; D001794:Blood Pressure; D005246:Feedback; D005665:Furosemide / Q000494:pharmacology; D006706:Homeostasis; D007678:Kidney Glomerulus / Q000502:physiology; D007684:Kidney Tubules / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008297:Male; D009399:Nephrons / Q000098:blood supply*; D010507:Periodicity; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005665:Furosemide