Keong C H, Kurumaji Y, Nishioka K
Department of Dermatology, School of Medicine, Tokyo Medical and Dental University, Japan.
Photodermatol Photoimmunol Photomed. 1990 Dec;7(6):237-42.
The interaction of ultraviolet A (UVA) and UVB in producing delayed pigmentation was quantitatively studied on the backs of 19 healthy Japanese subjects. The minimal pigementation dose for UVA (MPDA) and UVB (MPDB) was first determined using narrow-band radiation of 360 nm and 290 nm respectively. The average MPDA and MPDB was 16.4 J/cm2 and 32.9 mJ/cm2 respectively. In experiment 1, fractional doses of 0.2, 0.4, 0.6 and 0.8 MPDA were first irradiated on 4 sites each. Immediately following each exposure, fractional doses of either 0.2, 0.4, 0.6 or 0.8 MPDB were superimposed on the same sites, resulting in each exposure site receiving a different combination of fractions of MPDA and MPDB (A + B). This was repeated with the sequence of exposure reversed (B + A). The results demonstrated that the wavelengths interacted via photoaddition in producing delayed pigmentation, irrespective of the order of exposure. When a 3-h time interval was allowed between exposures in experiment 2, there was again no evidence of deviation from photoaddition with either order of exposure. This study shows that subthreshold doses of UVA and UVB interact additively in the production of delayed pigmentation.
在19名健康日本受试者的背部，对紫外线A（UVA）和紫外线B（UVB）在产生延迟性色素沉着方面的相互作用进行了定量研究。首先分别使用360nm和290nm的窄带辐射确定UVA（MPDA）和UVB（MPDB）的最小色素沉着剂量。MPDA和MPDB的平均值分别为16.4J/cm²和32.9mJ/cm²。在实验1中，首先在4个部位分别照射0.2、0.4、0.6和0.8倍MPDA的分次剂量。每次照射后，立即在相同部位叠加0.2、0.4、0.6或0.8倍MPDB的分次剂量，使得每个照射部位接受不同组合的MPDA和MPDB分次剂量（A + B）。以相反的照射顺序（B + A）重复此操作。结果表明，无论照射顺序如何，两种波长在产生延迟性色素沉着方面通过光加成相互作用。在实验2中，当两次照射之间留出3小时的时间间隔时，同样没有证据表明无论照射顺序如何都会偏离光加成。这项研究表明，低于阈值剂量的UVA和UVB在产生延迟性色素沉着方面以相加的方式相互作用。
