title: Reflex vasoconstriction in aged human skin increasingly relies on Rho kinase-dependent mechanisms during whole body cooling.
abstract: 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 degrees 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 (%DeltaCVC(baseline)). VC was reduced at the control site in O during cooling (Y, -34 + or - 3; and O, -18 + or - 3%DeltaCVC(baseline); P < 0.001) and NE infusion (Y, -53 + or - 4, and O, -41 + or - 9%DeltaCVC(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 + or - 5; and O, -7 + or - 1%DeltaCVC(baseline); P = 0.016) and was not altered by NOS inhibition. Fasudil blunted NE-mediated VC in both age groups (Y, -23 + or - 4; and O, -7 + or - 3%DeltaCVC(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.
authors.affiliation: Department of Kinesiology, The Pennsylvania State Univ., 229 Noll Lab., University Park, PA 16802, USA. jal493@psu.edu
authors.forename: James A
authors.initials: JA
authors.lastname: Lang
authors.forename: John D
authors.initials: JD
authors.lastname: Jennings
authors.forename: Lacy A
authors.initials: LA
authors.lastname: Holowatz
authors.forename: W Larry
authors.initials: WL
authors.lastname: Kenney
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000008:administration & dosage / Q000031:analogs & derivatives; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001808:Blood Vessels / Q000201:enzymology / Q000294:innervation; D001833:Body Temperature Regulation; D003080:Cold Temperature; D005260:Female; D005542:Forearm; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D017551:Microdialysis; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000294:innervation*; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000008:administration & dosage; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009599:Nitroprusside / Q000008:administration & dosage; D009638:Norepinephrine / Q000008:administration & dosage; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D012018:Reflex / Q000187:drug effects; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000008:administration & dosage; D055815:Young Adult; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D020030:Nitric Oxide Donors; D047428:Protein Kinase Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D009569:Nitric Oxide; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D019001:Nitric Oxide Synthase; D054460:rho-Associated Kinases; C049347:fasudil; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine