Are the prejunctional histamine receptors on sympathetic nerve terminals in guinea-pig isolated atria activated during anaphylaxis in vitro?

Abstract

Abstract In isolated atria from sensitized guinea-pigs, antigenic challenge with ovalbumin induces an anaphylactic reaction in which there is an increased rate and force of contraction. At the same time, stimulation-induced release of [3H]noradrenaline is inhibited by 40%. Cimetidine decreased the tachycardia occurring during anaphylaxis but had no effect on the inhibition of stimulation-induced transmitter release. It is known that antigenic challenge of sensitized guinea-pig atria releases histamine from mast cells; this histamine acts postjunctionally to increase heart rate. However, the inhibition of noradrenergic transmitter release is not due to the stimulation of prejunctional inhibitory histamine receptors.