This Article Full Text Full Text (PDF) All Versions of this Article: 40/1/74    most recent 01.HYP.0000022571.86090.F3v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Giannattasio, C. Articles by Mancia, G. Search for Related Content PubMed PubMed Citation Articles by Giannattasio, C. Articles by Mancia, G. Related Collections Endothelium/vascular type/nitric oxide

(Hypertension. 2002;40:74.)
© 2002 American Heart Association, Inc.

Scientific Contributions

Effects of Hematocrit Changes on Flow-Mediated and Metabolic Vasodilation in Humans

Cristina Giannattasio; Alberto Piperno; Monica Failla; Anna Vergani; Giuseppe Mancia

From the Clinica Medica, University of Milano Bicocca and San Gerardo Hospital (C.G., A.P., M.F., A.V., G.M.), Monza; Centro Fisiologia Clinica e Ipertensione (G.M.), Milano; and IRCCS Ospedale San Luca (C.G., G.M.), Milano, Italy.

Correspondence to Prof Giuseppe Mancia, Clinica Medica, Ospedale S. Gerardo, Via Donizetti 106, 20052 Monza (MI), Italy. E-mail giuseppe.mancia{at}unimib.it

Endothelial function is noninvasively assessed by measuring nitric oxide–dependent increase in radial artery diameter accompanying the elevation in shear stress induced by increasing blood flow through a short-lasting ischemia of the hand. However, shear stress also depends on blood viscosity, whose changes might thus affect nitric oxide increase in a manner that is not properly reflected by blood flow changes. In 12 subjects with hemochromatosis, we measured ultrasonographically radial artery diameter and blood flow responses to a 4-minute ischemia of the hand. This was done also after removing 500 mL of blood (and concomitantly infusing 500 mL of saline), which significantly (P<0.01) reduced hemoglobin concentration and hematocrit. The increase in blood flow induced by the 4-minute ischemia was similar before and after blood removal (+76% and +80%), which, in contrast, markedly attenuated the accompanying increase in radial artery diameter (+25% versus +13%, P<0.01). Thus, in humans, blood viscosity is involved in the endothelial response to an increase in shear stress. This implies that this response may not be accurately assessed and compared by quantifying the stimulus only through an increase in blood flow.

Key Words: blood flow • vasodilation • endothelium • hemoglobin • viscosity

This article has been cited by other articles:

				C. M. Boulanger, N. Amabile, A. P. Guerin, B. Pannier, A. S. Leroyer, Z. Mallat, C. Nguyen, A. Tedgui, and G. M. London In Vivo Shear Stress Determines Circulating Levels of Endothelial Microparticles in End-Stage Renal Disease Hypertension, April 1, 2007; 49(4): 902 - 908. [Abstract] [Full Text] [PDF]

				F. H. Verbeke, M. Agharazii, P. Boutouyrie, B. Pannier, A. P. Guerin, and G. M. London Local Shear Stress and Brachial Artery Functions in End-Stage Renal Disease J. Am. Soc. Nephrol., February 1, 2007; 18(2): 621 - 628. [Abstract] [Full Text] [PDF]

				P. Narayan, V. Papademetriou, K. Wachtell, E. Gerdts, K. Boman, M. S. Nieminen, G. de Simone, B. Dahlof, F. Fyhrquist, A. Hoieggen, et al. Association of Hemoglobin Delivery With Left Ventricular Structure and Function in Hypertensive Patients: Losartan Intervention For End Point Reduction in Hypertension Study Hypertension, May 1, 2006; 47(5): 868 - 873. [Abstract] [Full Text] [PDF]

				A. Natali, E. Toschi, S. Baldeweg, A. Casolaro, S. Baldi, A. M. Sironi, J. S. Yudkin, and E. Ferrannini Haematocrit, type 2 diabetes, and endothelium-dependent vasodilatation of resistance vessels Eur. Heart J., March 1, 2005; 26(5): 464 - 471. [Abstract] [Full Text] [PDF]

				K. E. Pyke, E. M. Dwyer, and M. E. Tschakovsky Impact of controlling shear rate on flow-mediated dilation responses in the brachial artery of humans J Appl Physiol, August 1, 2004; 97(2): 499 - 508. [Abstract] [Full Text] [PDF]