Formation and Binding of Histamine by Rat Tissues <i>In Vitro</i>

Abstract

Several rat tissues decarboxylate C 14 l-histidine and bind the resulting histamine in stable form. The pyloric portion of the stomach is by far the most active. Pretreatment of the rats with cortisone appears to reduce the histamine-binding activity of most tissues while prior adrenalectomy increases it. The stomach is the exception; here the reverse is true. Using rat lung as a test tissue, it was found that prednisone, prednisolone and 9-α-fluorohydrocortisone appear to be more active than cortisone or hydrocortisone in inhibition of histame bininding. The mechanism of this reduction of histamine-binding activity of rat lung involves the loss of extractable histidine decarboxylase activity.