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This Article Full Text Full Text (PDF) All Versions of this Article: 297/5/H1792    most recent 00509.2009v1 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 Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Lang, J. A. Articles by Kenney, W. L. PubMed PubMed Citation Articles by Lang, J. A. Articles by Kenney, W. L.

Reflex vasoconstriction in aged human skin increasingly relies on Rho kinase-dependent mechanisms during whole body cooling

¹Department of Kinesiology, Noll Labortory, and ²Graduate Physiology Program, The Pennsylvania State University, University Park, Pennsylvania

Submitted June 5, 2009 ; accepted in final form August 21, 2009

Primary human aging may be associated with augmented Rho kinase (ROCK)-mediated contraction of vascular smooth muscle and ROCK-mediated inhibition of nitric oxide synthase (NOS). We hypothesized that the contribution of ROCK to reflex vasoconstriction (VC) is greater in aged skin. Cutaneous VC was elicited by 1) whole body cooling [mean skin temperature (T_sk) = 30.5°C] and 2) local norepinephrine (NE) infusion (1 x 10^–6 M). Four microdialysis fibers were placed in the forearm skin of eight young (Y) and eight older (O) subjects for infusion of 1) Ringer solution (control), 2) 3 mM fasudil (ROCK inhibition), 3) 20 mM N^G-nitro-L-arginine methyl ester (NOS inhibition), and 4) both ROCK + NOS inhibitors. Red cell flux was measured by laser-Doppler flowmetry over each site. Cutaneous vascular conductance (CVC) was calculated as flux/mean arterial pressure and normalized to baseline CVC (%CVC_baseline). VC was reduced at the control site in O during cooling (Y, –34 ± 3; and O, –18 ± 3%CVC_baseline; P < 0.001) and NE infusion (Y, –53 ± 4, and O, –41 ± 9%CVC_baseline; P = 0.006). Fasudil attenuated VC in both age groups during mild cooling; however, this reduction remained only in O but not in Y skin during moderate cooling (Y, –30 ± 5; and O, –7 ± 1%CVC_baseline; P = 0.016) and was not altered by NOS inhibition. Fasudil blunted NE-mediated VC in both age groups (Y, –23 ± 4; and O, –7 ± 3%CVC_baseline; P < 0.01). Cumulatively, these data indicate that reflex VC is more reliant on ROCK in aged skin such that approximately half of the total VC response to whole body cooling is ROCK dependent.

skin blood flow; aging; temperature regulation; norepinephrine