title: Sympathetic, sensory, and nonneuronal contributions to the cutaneous vasoconstrictor response to local cooling.
abstract: Previous work indicates that sympathetic nerves participate in the vascular responses to direct cooling of the skin in humans. We evaluated this hypothesis further in a four-part series by measuring changes in cutaneous vascular conductance (CVC) from forearm skin locally cooled from 34 to 29 degrees C for 30 min. In part 1, bretylium tosylate reversed the initial vasoconstriction (-14 +/- 6.6% control CVC, first 5 min) to one of vasodilation (+19.7 +/- 7.7%) but did not affect the response at 30 min (-30.6 +/- 9% control, -38.9 +/- 6.9% bretylium; both P < 0.05, P > 0.05 between treatments). In part 2, yohimbine and propranolol (YP) also reversed the initial vasoconstriction (-14.3 +/- 4.2% control) to vasodilation (+26.3 +/- 12.1% YP), without a significant effect on the 30-min response (-26.7 +/- 6.1% YP, -43.2 +/- 6.5% control; both P < 0.05, P > 0.05 between sites). In part 3, the NPY Y1 receptor antagonist BIBP 3226 had no significant effect on either phase of vasoconstriction (P > 0.05 between sites both times). In part 4, sensory nerve blockade by anesthetic cream (Emla) also reversed the initial vasoconstriction (-20.1 +/- 6.4% control) to one of vasodilation (+213.4 +/- 87.0% Emla), whereas the final levels did not differ significantly (-37.7 +/- 10.1% control, -37.2 +/- 8.7% Emla; both P < 0.05, P > 0.05 between treatments). These results indicate that local cooling causes cold-sensitive afferents to activate sympathetic nerves to release norepinephrine, leading to a local cutaneous vasoconstriction that masks a nonneurogenic vasodilation. Later, a vasoconstriction develops with or without functional sensory or sympathetic nerves.
authors.affiliation: Dept. of Physiology-MSC 7756, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA. johnson@uthscsa.edu).
authors.forename: John M
authors.initials: JM
authors.lastname: Johnson
authors.forename: Tony C
authors.initials: TC
authors.lastname: Yen
authors.forename: Kun
authors.initials: K
authors.lastname: Zhao
authors.forename: Wojciech A
authors.initials: WA
authors.lastname: Kosiba
mesh_terms: D018674:Adrenergic Antagonists / Q000008:administration & dosage; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage; D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage; D001950:Bretylium Tosylate / Q000008:administration & dosage; D003080:Cold Temperature; D005260:Female; D006801:Humans; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors; D012867:Skin / Q000098:blood supply* / Q000294:innervation; D012881:Skin Temperature / Q000187:drug effects / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D015016:Yohimbine / Q000008:administration & dosage
chemical_list: D018674:Adrenergic Antagonists; D000317:Adrenergic alpha-Antagonists; D000779:Anesthetics, Local; D017476:Receptors, Neuropeptide Y; C097212:neuropeptide Y-Y1 receptor; D015016:Yohimbine; D001950:Bretylium Tosylate