Cutaneous reaction to prostaglandins E1,E2 and F2α in the bovine

Recent findings have shown that some prostaglandins of the E series induce inflammatory responses in the guinea-pig (Horton, 1963), rat (Kaley & Weiner, 1968; Arora, Lahiri & Sanyal, 1970; Crunkhorn & Willis, 1971a) and man (Bergstrom, Duner & others, 1959; Solomon, Juhlin & Kirschenbaum, 1968; Crunkhorn & Willis, 1971a; S~ndergaard & Greaves, 1971 ; Greaves, Smdergaard & McDonald-Gibson, 1971). We have been interested in the dermal responses of cattle to histamine, 5-HT, kinins, and in passive cutaneous anaphylaxis (Wells & Eyre, 1970), and in view of the inflammatory potency of prostaglandins, and the suggestion by Crunkhorn & Willis (1971a & b) that cutaneous reactions to prostaglandins may be a consequence of liberated histamine, it seemed of interest to investigate these compounds in the bovine species. Male Guernsey or Jersey calves, 30-50 kg, and aged 4 to 8 wk were depilated using calcium thioglycolate cream (Wells & Eyre, 1970). Five per cent Pontamine blue solution (E. Gurr Ltd., London, England) (0.6 ml/kg, i.v.) was administered immediately before 0.2 ml intradermal injections of various concentrations of prostaglandins (PGs) El, E,, and F,a, compound 48/80, histamine acid phosphate, 5-hydroxytryptamine creatinine sulphate monohydrate (5-HT) and bradykinin triacetate were made. All injected compounds were dissolved in isotonic sodium chloride solution. PGs El, E,, and F,a were freshly prepared by diluting stock solutions containing 100 pg/ml in 95% ethanol. Skin-reactions appeared as ovoid or circular blue wheals and were measured with calipers at 30 min (maximal response). A threshold reading of 1.0 cm was established arbitrarily on the basis that intradermal injections of 0.2 ml saline gave skin-reaction diameters of 0.4-0.8 cm. The results are in Table 1. Intradermal injections of PGE,, PGE,, PGF,a, compound 48/80 and isotonic saline were made in three calves anaesthetized with pentobarbitone. Subcutaneous tissues adjacent to the skin-reactions were removed at 5, 60 and 120 min, fixed in 80% ethanol, stained with toluidine blue (Riley, 1959) and examined for mast cell changes. Mepyramine maleate (5 mg/kg) was administered 30 min before similar intradermal injections in a further two animals. Histamine, bradykinin, PGE, and PGE, produced increased permeability within 5 min of intracutaneous injection. The potencies of PGE, and PGE, were similar to each other on a weight basis, but greater than either histamine or bradykinin. PGF,a produced no observable increase in vascular permeability although at high