EFFECTS OF METHYSERGIDE ADMINISTRATION ON EDEMA FORMATION AT THE SITEOF SCALD

Femoral blood flow (Qa), hind paw lymph flow (Qlym), and lymph-to-plas ma protein concentration ratio (C-lym/C-p) were monitored before and 4 h after 1) 5-s 100 degrees C paw scald, 2) methysergide (1 mg/kg iv) 20 min before scald, 3) methysergide 30 min after scald, and 4) methys ergide only. Before experimentation, hind paw venous pressure was elev ated and maintained until steady-state Qa, Qlym, and minimal C-lym/C-P levels were reached. The reflection coefficient (sigma(d)) was determ ined as 1 - minimal C-lym/C-P; the filtration coefficient (K-f) was ca lculated. Methysergide alone caused no changes. Increases in Qa, Qlym, C-lym/C-P, and K-f were identified in all scald groups. Compared with scald only animals, and postscald methysergide blunted the increases in Qa, Qlym, K-f, and paw weight gain without an effect on sigma(d). T hese data demonstrate that methysergide reduces edema formation at the site of scald, perhaps by modulating the burn-induced vasodilator res ponse and/or by limiting the burn-induced increase in microvascular su rface area.