Effect of infrared irradiation on the recoverable levels of free arachidonic acid and prostaglandins in human forearm skin.

The inside skin of the forearm of healthy volunteers was irradiated with an infrared (IR) lamp for 1 hr, resulting in the rapid appearance of an erythema and an elevation of skin surface temperature from 30 +/- 1 degree C to 38 +/- 2 degrees C within 5 min. The erythema and elevated skin surface temperature decayed within 10-30 min when the IR irradiation was stopped. Suction blisters were raised on nonirradiated skin and on irradiated skin both during irradiation and at various times after irradiation stopped. Elevated levels of free arachidonic acid, PGE2, PGD2, PGF2 alpha and 6-oxo-PGF1 alpha were found up to 24 h after irradiation. By 48 h the prostaglandin levels had returned to control values whereas the free arachidonic acid levels were still elevated at 72 h. The peak level of 6-oxo-PGF1 alpha appears between 0-6 h whereas for PGE2, D2, and F2 alpha it is between 6-16 h, suggesting a different cellular source for this prostaglandin.