Modulation of vascular tone in renal microcirculation by erythrocytes: role of EDRF.
The effect of erythrocytes (red blood cells, RBC) on vascular tone in the renal microcirculation was examined using the juxtamedullary nephron microvascular preparation perfused in vitro with a physiological salt solution containing 5% albumin. The basal diameters of the arcuate, interlobular, proximal, and distal afferent arterioles averaged 444 +/- 24, 74 +/- 3, 29 +/- 1, and 19 +/- 1 micron, respectively, when perfused with a cell-free solution at a pressure of 80 mmHg. The diameters of the arcuate and interlobular arteries increased by 14 +/- 4 and 13 +/- 4%, respectively, whereas the diameter of the proximal and distal portions of the afferent arterioles decreased by 7 +/- 2% when perfusion pressure was elevated from 80 to 160 mmHg. The addition of RBC to the perfusate reduced the basal diameters of interlobular and afferent arterioles by 11 +/- 4 and 15 +/- 3%, respectively. The maximal vasoconstrictor response was seen after the addition of only 1% RBC to the perfusate. Removal of platelets did not block the vasoconstrictor response to addition of RBC to the perfusate. The role of endothelium-derived relaxing factor (EDRF) in the vasoconstrictor response to RBC was studied by addition of nitric oxide synthase inhibitor, N omega-nitro-L-arginine (L-NNA, 100 microM) to the perfusate. L-NNA reduced the basal diameters of interlobular and afferent arterioles by 7 +/- 3 and 9 +/- 3%, respectively, and abolished the vasoconstrictor response to RBC. L-NNA had no effect on the pressure-diameter relationships of the preglomerular vasculature when added to perfusates already containing RBC.(ABSTRACT TRUNCATED AT 250 WORDS)
Imig
J D
JD
Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
Gebremedhin
D
D
Harder
D R
DR
Roman
R J
RJ
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001792:Blood Platelets / Q000502:physiology; D001808:Blood Vessels / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology*; D008297:Male; D008833:Microcirculation; D009569:Nitric Oxide / Q000502:physiology*; D019335:Nitroarginine; D010100:Oxygen / Q000378:metabolism; D010108:Oxyhemoglobins / Q000378:metabolism; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation; D014661:Vasoconstriction / Q000187:drug effects; D014666:Vasomotor System / Q000502:physiology*
D010108:Oxyhemoglobins; D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D010100:Oxygen