SUBSTANCE-P LEVEL IS INCREASED IN THE CHOLESTEROL INDUCED ANAPHYLACTOID REACTION IN THE PIG

The role of substance P (SP) in cholesterol-induced anaphylactoid reac tion was investigated in 13 Landrace pigs. Pigs were anesthetized with sodium thiopental and ventilation was controlled with 70% nitrous oxi de in oxygen. A Swan-Ganz catheter and a carotid arterial line were pl aced to monitor the hemodynamic data. Group 1 pigs (control group, n = 5) each received 20 mi of intravenous (IV) colloid infusion solution (Haemaccel) and group 2 pigs (cholesterol group, n = 8) each received an IV injection of pure cholesterol emulsion (12 mg/kg) in 20 ml of Ha emaccel. Blood samples for SP and histamine (H) levels were taken just before and for 10 min following the placebo, Haemaccel, and cholester ol injections. Urine samples were also collected just before and at 60 min following the injections for methyl histamine (MH) levels, Group 2 pigs (cholesterol) developed an anaphylactoid reaction as indicated by marked and significant hemodynamic changes. None of the group 1 (pl acebo) pigs developed an anaphylactoid reaction. Significant increases in blood SP and H levels (P < 0.05), and urine MH levels (P < 0.05) w ere seen in cholesterol-treated pigs (group 2), whereas no significant changes were seen in control pigs (group 1). Our results suggest that SP is involved in the cholesterol-induced anaphylactoid reaction in p igs.