Non cytotoxic guinea-pig mesenteric mast cell stimulation by protamine.

Protamine stimulates guinea-mesenteric mast cells in a concentration-dependent manner, both histamine release and mast cell degranulation being correlated. Mast cell stimulation is blocked by 2,4-DNP (0.03 mM), low (0 degrees C) and high (45 degrees C) temperature. The inhibitory effect by 2,4-DNP is reversed by glucose (5.0 mM), while incubation at 37 degrees reverses that by low and high temperature. Lack of calcium from the incubation medium does not influence mast cell stimulation by protamine. However calcium chelation with EDTA (2.0 mM) or EGTA (2.0 mM) blocks mast cell stimulation. Addition of calcium (0.9 mM) reverses this inhibition. These observations indicate that guinea-pig mast cell stimulation by protamine is a nonlytic, energy and calcium dependent process, similar to anaphylaxis, but different from that of other basic compounds which induce mast cell lysis.