Interrelationship of cyclic nucleotides and anaphylactic reactions

THE mode of action of several anti-allergic drugs, which are structurally diverse, has been studied by comparing their inhibition of cyclic nucleotide phosphodiesterase with inhibition of anaphylaxis. The cyclic nucleotide phosphodiesterase activities were measured in microsomal preparations of both human and sheep lung, and the anaphylaxis was observed in vitro in passively sensitised human lung and in rats in vivo (passive cutaneous anaphylaxis (PCA)). A significant correlation has been found between the inhibition of anaphylaxis and the ratio of the inhibition of hydrolysis of cyclic AMP to the inhibition of hydrolysis of cyclic GMP. A less significant correlation was also found between inhibition of rat PCA and inhibition of hydrolysis of cyclic GMP.