测量人体皮肤缓冲能力：一种体外模型。

Department of Dermatology, School of Medicine, University of California, San Francisco, CA 94143-0989, USA.

Skin Res Technol. 2009 Nov;15(4):470-5. doi: 10.1111/j.1600-0846.2009.00392.x.

BACKGROUND/PURPOSE: It has been thought that skin possesses buffering capacity. This study measured the skin buffering capacity against two model solutions of acid and base at three concentrations with an in vitro system.

METHODS

Ten microliters of model base (sodium hydroxide--NaOH) and acid (hydrochloric acid--HCl) solutions at concentrations of 0.025, 0.05, and 0.1 N was applied to human cadaver skin (3.18 microL/cm(2)) placed onto glass diffusion cells. Phosphate-buffered saline (PBS) was used as a standard buffer solution. Deionized water served as the negative control, whereas untreated skin served as the blank control. Skin pH was read and recorded immediately following dosing (0 time), and at 10 and 30 min of post-dosing. After the 30 min of dosing, each skin, except untreated skin (blank control), was then washed by applying 1 cm(3) of deionized water. The pH on each washed skin was measured immediately following washing, and the pH measurement was repeated at 10 and 30 min of post-washing. Six replicates were conducted.

RESULTS

The pH values sharply significantly increased (P<0.05) immediately following dosing with NaOH at all concentrations (the highest concentration, caused the highest pH), and then decreased closely to baselines within 30 min post-application but still remained at significantly (P<0.05) higher values when compared with the blank control (untreated skin). HCl (acid) significantly (P<0.05) decreased skin pH immediately following dosing with all concentrations (the highest concentration, caused the lowest pH) and then restored rapidly to baseline. There was no significant difference in post-washing procedures on the skins that were pre-treated with the acid (HCI) solutions. However, with all base solutions (NaOH) pre-treated skin, pH values were significantly higher (P<0.05) at all time points post-washing. Furthermore, both PBS and water controls significantly elevated (P<0.05) the pH values following washing.

CONCLUSION

Skin pH and its buffering capacity can be measured on human cadaver skin in vitro, which may partially replicate the response of in vivo skin. Dose-response was noted; i.e. the higher concentration caused larger changes in skin pH. In addition, the restoration of skin pH is relatively faster with acid when compared with base treatment. Clinical implications are offered.

背景/目的：人们一直认为皮肤具有缓冲能力。本研究通过体外系统，用两种酸（盐酸）和碱（氢氧化钠）模型溶液，在三个浓度下，测量皮肤的缓冲能力。

方法

将 10 微升 0.025、0.05 和 0.1 N 的模型碱（氢氧化钠）和酸（盐酸）溶液分别滴注在置于玻璃扩散池的人体尸体皮肤上（3.18 微升/平方厘米）。磷酸盐缓冲盐水（PBS）用作标准缓冲溶液。去离子水作为阴性对照，未经处理的皮肤作为空白对照。滴注后即刻（0 时间）、滴注后 10 和 30 分钟时，读取并记录皮肤 pH 值。滴注 30 分钟后，除未经处理的皮肤（空白对照）外，每个皮肤均用 1 立方厘米的去离子水冲洗。冲洗后立即测量每个冲洗过的皮肤的 pH 值，冲洗后 10 和 30 分钟时再次测量 pH 值。进行了 6 次重复实验。

结果

NaOH 所有浓度（最高浓度导致最高 pH 值）滴注后，皮肤 pH 值立即显著升高（P<0.05），30 分钟后接近基线，但与空白对照（未经处理的皮肤）相比仍显著升高（P<0.05）。所有浓度（最高浓度导致最低 pH 值）HCl（酸）滴注后，皮肤 pH 值立即显著降低（P<0.05），然后迅速恢复到基线。用酸（HCl）溶液预处理的皮肤在冲洗后程序中没有显著差异。然而，用所有碱（NaOH）溶液预处理的皮肤，冲洗后所有时间点的 pH 值均显著升高（P<0.05）。此外，PBS 和水对照在冲洗后均显著升高（P<0.05）皮肤 pH 值。