Rho-Kinase activity and cutaneous vasoconstriction is upregulated in essential hypertensive humans

Abstract

Essential hypertension (HT) is associated with endothelial dysfunction augmented vasoconstriction (VC) which may be secondary to increased Rho/Rho-Kinase (ROCK)-dependent mechanisms. Our aim was to assess the in vivo magnitude of cutaneous VC to local cooling as a ROCK specific stimulus, and in vitro evaluate ROCK activity in the skin from HT humans. Four microdialysis fibers were placed in the forearm of 9 pre- to stage I hypertensive (MAP: 106±3mm Hg) and 11 normotensive (NT; 86±1mm Hg) men and women: Ringers (control), 3mM fasudil (ROCK inhibited), 5mM yohimbine+1mM proprananol (α- and β-adrenoceptor inhibited; Y+P), Y+P+3mM fasudil (ROCK and adrenocepor inhibited). Skin blood flow was measured during local cooling (Tskl 24°C) and ROCK activity in the skin biopsy samples was determined with western blot. In vitro phosphorylated myosin phosphatase target subunit 1 (pMYPT-1)/ROCK was increased in the HT skin samples (p=0.0018). Functionally, no difference in basal vasomotor tone (Tskl 34°C) was observed between the groups (HT: 0.36±0.07 vs. NT: 0.31±0.07 CVC), nor at the control site during local cooling. Pre- to stage 1 hypertensives show greater ROCK-mediated vasoconstriction at early (1–5min; HT: −0.8±0.2 versus NT: −0.3±0.2 ΔCVC baseline 1; P<0.0001) and late (36–40min; HT: −0.9±0.1 versus NT: −0.5±0.2 ΔCVC baseline 1; P<0.0001) phases of local cooling. These data suggest that the magnitude of cutaneous vasoconstriction to local cooling does not differ in normotensive and pre- to stage I essential hypertensive humans; however, ROCK activity is increased and functional vasoconstriction is increasingly dependent upon Rho/ROCK mechanisms with essential hypertension.