Schultz-Dale reaction in isolated perfused calf ear and its inhibition by isoproterenol

Calf ears which were sensitised to horse serum and others which were unsensitised were catheterised and perfused at a constant flow rate of 2 ml min-1 with Krebs-Henseleit solution using a peristalic pump. The ear preparations were then challenged with whole horse serum, the sensitising antigen. Vascular responses were monitored as changes in perfusion pressure. Weight changes were determined to indicate the extent of oedema formation. Unsensitised ear preparations responded to 0.1 ml whole horse serum with 43.3 +/- 0.8 per cent (n = 5) and 10.7 +/- 0.3 per cent (n = 5) increases in perfusion pressure and weight, respectively. Sensitised ear preparations responded to 0.05 ml whole horse serum by increases of 280.8 +/- 32.9 per cent (n = 5) and 27.2 +/- 1.4 per cent (n = 5) in perfusion pressure and bodyweight, respectively. Isoproterenol (10(-5) M) inhibited the vascular responses by 81.4 +/- 7.6 per cent (n = 5) while the increases in weight were reduced by 20.0 +/- 1.5 per cent (n = 5). The Schultz-Dale reaction has thus been demonstrated in an isolated whole organ, the pinna.