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  • The effect of alpha-adrenoceptor agonists and L-NMMA on cutaneous postocclusive reactive hyperemia
    Cankar, Ksenija, 1965- ; Finderle, Žarko ; Štrucl, Martin
    Postocclusive reactive hyperemia (PRH) is considered to be a locally mediated vascular reaction independent of sympathetic activity. However, experiments onanimal vascular preparations have shown ... that alpha(2)-adrenoceptor activity interferes with the production of endothelium-derived nitric oxide (NO) that has been found to play an important role in the PRH response. We attempted toelucidate the role of endothelium-derived NO in the cutaneous PRH response. Especially, we aimed to clarify the interference of the alpha-adrenoceptor activity with NO mechanism in cutaneous microcirculation. We studied the effect of intradermal microinjection of the NO synthase inhibitor L-NMMA alone, alpha(1)-agonist phenylephrine alone, alpha(2)-agonist clonidine alone and L-NMMA in combination with each alpha-agonist. The effect of the saline solution injection was used as a reference value. Laser-Doppler flux was monitored in 11 healthy volunteers before and after a 4-minute and an 8-minuteocclusion of digital arteries. The application of L-NMMA significantlyreduced resting LD-flux (p<0.05) only in combination with alpha(2)-agonist but not alpha(1)-agonist. The application of L-NMMA alone changed the time in which LD flux reached half of the preocclusive value during the PRH response (T/2) only after 4-minute (p<0.05) but not after an 8-minute occlusion. Phenylephrine (alpha(1)-agonist) alone shortened (p<0.05),while clonidine (alpha(2)-agonist) alone prolonged T/2 (p<0.05) of 8-minute PRH. The combined application of L-NMMA and clonidine abolished the effect of clonidine alone on 8-minute PRH. In contrast, the combination of L-NMMA and phenylephrine did not cause any change of the PRH response when compared to the injection of phenylephrine alone. (Abs. trunc. at 2000 ch.)
    Source: Microvascular research. - ISSN 0026-2862 (Vol. 77, no. 2, 2009, str. 198-203)
    Type of material - article, component part ; adult, serious
    Publish date - 2009
    Language - english
    COBISS.SI-ID - 25860569
    DOI

source: Microvascular research. - ISSN 0026-2862 (Vol. 77, no. 2, 2009, str. 198-203)
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