Department of Physiology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic.
Physiol Res. 2023 Jun 9;72(S1):S1-S9. doi: 10.33549/physiolres.935018.
During phototherapy of jaundiced newborns, vasodilation occurs in the skin circulation compensated by vasoconstriction in the renal and mesenteric circulation. Furthermore, there is a slight decrease in cardiac systolic volume, and blood pressure, as well as an increase in heart rate and discrete changes in the heart rate variability (HRV). The primary change during phototherapy is the skin vasodilation mediated by multiple mechanisms: 1) Passive vasodilation induced by direct skin heating effect of the body surface and subcutaneous blood vessels, modified by myogenic autoregulation. 2) Active vasodilation mediated via the mechanism provided by axon reflexes through nerve C-fibers and humoral mechanism via nitric oxide (NO) and endothelin 1 (ET-1). During and after phototherapy is a rise in the NO:ET-1 ratio. 3) Regulation of the skin circulation through the sympathetic nerves is unique, but their role in skin vasodilation during phototherapy was not studied. 4) Special mechanism is a photorelaxation independent of the skin heating. Melanopsin (opsin 4) - is thought to play a major role in systemic vascular photorelaxation. Signalling cascade of the photorelaxation is specific, independent of endothelium and NO. The increased skin blood flow during phototherapy is enabled by the restriction of blood flow in the renal and mesenteric circulation. An increase in heart rate indicates activation of the sympathetic system as is seen in the measures of the HRV. High-pressure, as well as low-pressure baroreflexes, may play important role in these adaptation responses. The integrated complex and specific mechanism responsible for the hemodynamic changes during phototherapy confirm adequate and functioning regulation of the neonatal cardiovascular system, including baroreflexes.
在黄疸新生儿的光疗过程中，皮肤循环会出现血管扩张，而肾和肠系膜循环则会出现血管收缩以进行代偿。此外，心脏收缩量、血压会略有下降，心率会增加，心率变异性（HRV）也会出现离散变化。光疗过程中的主要变化是由多种机制介导的皮肤血管扩张：1）体表和皮下血管的直接皮肤加热效应引起的被动血管扩张，由肌源性自动调节修饰。2）通过神经 C 纤维的轴突反射和通过一氧化氮（NO）和内皮素 1（ET-1）的体液机制介导的主动血管扩张。在光疗期间和之后，NO:ET-1 比值升高。3）通过交感神经对皮肤循环的调节是独特的，但它们在光疗期间皮肤血管扩张中的作用尚未研究。4）特殊机制是一种不依赖皮肤加热的光松弛。黑视蛋白（视蛋白 4）被认为在全身血管光松弛中发挥主要作用。光松弛的信号级联是特定的，独立于内皮和 NO。光疗期间皮肤血流量增加是通过限制肾和肠系膜循环中的血流来实现的。心率的增加表明交感神经系统的激活，如 HRV 的测量所示。高、低血压压力反射可能在这些适应反应中发挥重要作用。光疗过程中血液动力学变化所涉及的综合复杂而特异的机制，证实了新生儿心血管系统包括压力反射在内的充分和有效的调节。
