Administration of PGF(2α) at doses of 50 and 250 μg into pouch fluid (calculated concentration of PGF(2α) was about 4 and 14 μg/ml of pouch fluid, respectively) of 7-day-old carrageenin granuloma in rats depressed vascular permeability, as measured by leakage of radioiodinated human serum albumin into the pouch fluid. However, 3 hr after PGF(2α) treatment at a dose of 50 μg, the vascular permeability had recovered to control level; 3 hr after a dose of 250 μg PGF(2α), the vascular permeability had not recovered completely. The uptake of [3H]proline into collagen hydroxyproline and noncollagenous protein of carrageenin granuloma tissue was also examined. It was found that the first injection of PGF(2α) at a dose of 50 or 250 μg depressed the uptake of [3H]proline into both protein fractions, but 3 hr after the first injection of PGF(2α), there was no significant difference in uptake between the control and the PGF(2α) treated group. A study of the metabolism of PGF(2α) in a homogenate of granulation tissue and in pouch fluid showed little activity in the former and very little activity in the latter. In the homogenate, about 70% of the originally added [3H]PGF(2α) remained unmetabolized after 3 hr of incubation. In the inflammatory fluid, less than 20% of the radioactivity present at 35 min after the injection had disappeared from the pouch fluid at 3 hr after the [3H]PGF(2α) injection; all the remaining radioactivity was found to be unmetabolized [3H]PGF(2α). Consequently, it was suggested that the tissue became desensitized to the injected PGF(2α). To confirm this suggestion, another 50 or 250 μg of PGF(2α) was injected 3 hr after the first PGF(2α) injection. However, a decrease in vascular permeability and in uptake of [3H]proline into both protein fractions after the second injection of PGF(2α) were not observed. It was concluded that, 3 hr after the first PGF(2α) treatment, the sensitivity of the carageenin-induced granulation tissue to PGF(2α) had decreased.
|Number of pages||8|
|Journal||Annals of Neurology|
|Publication status||Published - 1979 Jan 1|
ASJC Scopus subject areas
- Clinical Neurology