Increase in the Sensitivity of the Rat to Histamine Following Infection with <i>Nippostrongylus brasiliensi</i><i>s</i>

The present results show that following infection of rats with the nematode, &lt;i&gt;Nippostrongylus brasiliensis&lt;/i&gt;, the toxicity of histamine is increased but the hyperglycemic response to histamine and epinephrine is unchanged. In rats pretreated with &lt;i&gt;Haemophilus pertussis&lt;/i&gt; vaccine, on the contrary, the increase in toxicity to histamine is accompanied by a blockade of the hyperglycemic response to histamine and epinephrine. Further observations have shown that the hypersensitivity of nematode-infected rats to histamine is not diminished by pretreatment with &lt;i&gt;&amp;#914;&lt;/i&gt;-adrenergic blockers or cortisone together with L-epinephrine. Thus, blockade of the adrenergic function is not an important feature in the increase in histamine lethality of the nematode-infected rat.</jats:p