Subcutaneous blood flow in psoriasis.

The simultaneously recorded disappearance rates of 133Xe from subcutaneous adipose tissue in the crus were studied in 10 patients with psoriasis vulgaris using atraumatic labeling of the tissue in lesional skin (LS) areas and symmetrical, nonlesional skin (NLS) areas. Control experiments were performed bilaterally in 10 younger, healthy subjects. The subcutaneous washout rate constant was significantly higher in LS, 0.79 +/- 0.05 min-1 X 10(2) compared to the washout rate constant of NLS, 0.56 +/- 0.07 min-1. 10(2) (p less than 0.05), or the washout rate constant in the normal subjects, 0.46 +/- 0.17 min-1 X 10(2) (p less than 0.01). The mean washout rate constant in NLS was 25% higher than the mean washout rate constant in the normal subjects. The difference was, however, not statistically significant. Differences in the washout rate constants might be due to abnormal subcutaneous tissue-to-blood partition (lambda) in the LS--and therefore not reflecting the real differences in the subcutaneous blood flow (SBF). The lambda for 133Xe was therefore measured--using a double isotope washout method (133Xe and [131I]antipyrine)--in symmetrical sites of the lateral crus in LS and NLS of 10 patients with psoriasis vulgaris and in 10 legs of normal subjects. In LS the lambda was 4.52 +/- 1.67 ml/g, which was not statistically different from that of NLS, 5.25 +/- 2.19 ml/g (p less than 0.05), nor from that of normal subcutaneous tissue, 4.98 +/- 1.04 ml/g (p less than 0.05). Calculations of the SBF using the obtained lambda values gave a significantly higher SBF in LS, 3.57 +/- 0.23 ml/100 g/min, compared to SBF in the NLS, 2.94 +/- 0.37 ml/100 g/min (p less than 0.05). There was no statistically significant difference between SBF in NLS and SBF in the normal subjects. The increased SBF in LS of psoriatics might be a secondary phenomenon to an increased heat loss in the lesional skin.