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 x 0.12 mA, 200 s x 0.06 mA, 300 s x 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 andlt; 0.001). The decrease was 25-33%, depending on drug delivery rate. In unheated skin, a significant vasoconstriction was observed (p andlt; 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.
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机译：研究微血管对血管收缩药物离子电渗疗法的反应有助于更好地了解皮肤血管的调节机制，但是在基础血流情况下用激光多普勒血流仪测量这些反应在技术上具有挑战性。这项研究旨在调查通过局部电渗流对微血管床进行预扩张是否有助于通过离子电渗疗法测量对去甲肾上腺素（NA）和去氧肾上腺素（PE）的皮肤血管收缩反应的测量。我们使用了不同的药物传输速率（100 s x 0.12 mA，200 s x 0.06 mA，300 s x 0.04 mA）来研究预扩张是否会通过增加从皮肤上去除药物的方式来影响局部药物动力学。在预先扩张的血管床中，NA和PE的离子电渗疗法导致热平台的灌注显着降低（p <0.001）。减少幅度为25-33％，具体取决于药物的递送率。在未加热的皮肤中，观察到明显的血管收缩（p ＜0.001），NA和PE分别比基线降低17％和14％。这些结果表明，通过局部加热对皮肤血管床进行预扩张有助于通过激光多普勒血流仪进行血管收缩的测量，并且似乎不会通过增加药物从皮肤中的去除而显着影响结果。
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