Inhibition of antigen-induced histamine release by ouabain

Abstract

The effect of ouabain, a specific sodium-potassium dependent adenosine triphosphatase (Na +-K +-ATPase) inhibitor, on antigen-induced histamine release was studied using guinea pig lung fragments sensitized in vitro with rabbit antibodies against bovine serum albumin. Histamine was assayed spectrafluorometrically. When sensitized tissue had been preincubated with ouabain (≤ 1.0 × 10 −4 M) for 10 min prior to antigenic challenge, release of histamine was significantly inhibited (maximum 54%, p < 0.001, N = 9, paired t test). The most significant inhibition was obtained, near the optimal concentration of antigen. The inhibition was dependent on the length of preincubation (≤ 20 min), and was partially reversible upon washing the tissue removing the ouabain. Ouabain did not seem to prolong the duration of the histamine release process. Increase in potassium ion (≤ 1.1 × 10 −2 M) inhibited the histamine release and had additive effects to ouabain action. Dibutyryl cyclic AMP (≤ 5 × 10 −3 M), which could enhance the release, strongly antagonized the inhibition. Glucose removal from the medium did not abolish the ouabain effect. The results seem to indicate that immunologic release of histamine is under the influence of the membrane Na +-K +-ATPase activity.