title: Local heating as a predilatation method for measurement of vasoconstrictor responses with laser-Doppler flowmetry.
abstract: Studying microvascular responses to iontophoresis of vasoconstricting drugs contributes to a better understanding of the regulatory mechanisms of cutaneous vessels, but measuring these responses with laser-Doppler flowmetry at basal blood flow conditions is technically challenging. This study aimed to investigate whether the measurement of cutaneous vasoconstrictor responses to noradrenaline (NA) and phenylephrine (PE), delivered by iontophoresis, is facilitated by predilatation of the microvascular bed using local heating. We used different drug delivery rates (100 s × 0.12 mA, 200 s × 0.06 mA, 300 s × 0.04 mA) to investigate whether predilatation affects the local drug dynamics by an increased removal of drugs from the skin. In a predilatated vascular bed, iontophoresis of NA and PE resulted in a significant decrease in perfusion from the thermal plateau (p < 0.001). The decrease was 25-33%, depending on drug delivery rate. In unheated skin, a significant vasoconstriction was observed (p < 0.001), with 17% and 14% decrease from baseline for NA and PE, respectively. These results indicate that predilatating the cutaneous vascular bed by local heating facilitates measurement of vasoconstriction with laser-Doppler flowmetry and does not seem to significantly affect the result by an increased removal of drugs from the skin.
authors.affiliation: Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Joakim
authors.initials: J
authors.lastname: Henricson
authors.forename: Erik
authors.initials: E
authors.lastname: Tesselaar
authors.forename: Yashma
authors.initials: Y
authors.lastname: Baiat
authors.forename: Gert
authors.initials: G
authors.lastname: Nilsson
authors.forename: Folke
authors.initials: F
authors.lastname: Sjöberg
mesh_terms: D006361:Heating / Q000379:methods*; D006801:Humans; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D009638:Norepinephrine / Q000008:administration & dosage; D010656:Phenylephrine / Q000008:administration & dosage; D012867:Skin / Q000098:blood supply / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000528:radiation effects*
chemical_list: D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009638:Norepinephrine