Atrial natriuretic peptide increases microvascular blood flow and macromolecular escape during renin infusion in the hamster.
The effects of Atrial Natriuretic Peptide (ANP) on microvascular hemodynamics and macromolecular permselectivity were studied in the hamster cheek pouch under resting conditions and during intravenous renin infusion. Fluorescent intravital microscopy was used to observe arteriolar diameters and to detect escape of fluorescent dextran of 150 K-Daltons (FITC-Dx-150). Microvascular plasma flow was estimated by clearance of 51Cr-EDTA and net macromolecular transport by clearance of FITC-Dx-150. At rest, topical ANP (2-250 ng/ml) had no effect on arteriolar diameter, 51Cr-EDTA clearance, relative vascular conductance (RVC) or FITC-Dx-150 clearance. Infusion of renin (10 mU/Kg/Hr, iv) elevated systemic arterial pressure by 30% and reduced cheek pouch RVC by 26%. During renin infusion, topical ANP (50 ng/ml) produced transient arteriolar vasodilation, and increased 51Cr-EDTA clearance (+35%), RVC (+58%) and FITC-Dx-150 clearance (+54%), without affecting systemic pressure. ANP did not induce venular leakage sites under any condition, but changes in FITC-Dx-150 clearance were highly correlated with changes in 51Cr-EDTA clearance, suggesting that the larger macromolecular escape was due to increases in microvascular blood flow and capillary/post-capillary hydrostatic pressure.
Department of Physiology, Faculty of Biological Sciences, P. Universidad Catolica de Chile, Santiago.
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Borić
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Albertini
D000704:Analysis of Variance; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002199:Capillary Permeability / Q000187:drug effects; D002610:Cheek / Q000098:blood supply; D002860:Chromium Radioisotopes; D006224:Cricetinae; D003911:Dextrans; D004492:Edetic Acid / Q000493:pharmacokinetics; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives*; D005452:Fluoresceins; D007262:Infusions, Intravenous; D008297:Male; D008647:Mesocricetus; D008657:Metabolic Clearance Rate / Q000187:drug effects; D008833:Microcirculation / Q000187:drug effects*; D012083:Renin / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
D002860:Chromium Radioisotopes; D003911:Dextrans; D005452:Fluoresceins; C015219:fluorescein isothiocyanate dextran; D009320:Atrial Natriuretic Factor; D004492:Edetic Acid; D012083:Renin; D016650:Fluorescein-5-isothiocyanate