Abstract
Summary
Reactive hyperemic edema (RHE) was induced in hind paws of rats by application of a constriction band for 2, 5, 15, 30, or 60 min; 1 or 3 hr after removal of the band, swelling of the hind paws was measured. RHE was completely reversible within 2 to 4 days; none of the animals died. Attenuation of RHE was produced by the vasoconstrictor, α-sympathomimetic activity of norepinephrine, phenylephrine, or epinephrine; phentolamine antagonized this attenuation completely, but sotalol, a β-adrenergic receptor blocking agent, did not. Tripelennamine and methdilazine produced slight inhibition of RHE at much higher dose levels than those needed to reduce histamine-induced edema in hind paws; cyproheptadine (50 mg/kg, sc) was ineffective. Methysergide maleate (50.0 mg/kg) caused only a slight reduction of RHE (27%). Classical anti-inflammatory steroids were ineffective but indomethacin and phenylbutazone induced a small degree of reduction of RHE at high dosage. Narcotic analgesic/anti-inflammatory drugs, morphine, meperidine, and α-prodine, inhibited RHE according to their rank order of analgesic potency but none produced more than 49% inhibition. Atropine (75 mg/kg) and hexamethonium (100 mg/kg) did not diminish RHE. It is concluded that RHE may be induced by overstretched, fragile, smooth muscle of precapillary vessels; and constriction of the latter by an α-sympathomimetic action, either directly or indirectly (by affecting certain regions of the central nervous system which may be concerned with the peripheral release of α-sympathomimetics), inhibits the development of RHE. Histamine or serotonin are probably not involved in the development of RHE.
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