Involvement of Calcium and Cyclic AMP in Controlling Ixodid Tick Salivary Fluid Secretion

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Abstract
Catecholamine-stimulated salivary fluid secretion (in vitro) by ixodid ticks is reduced by deletion or lowering the concentration of exogenous bathing medium Ca2+. The Ca2+ antagonist, verapamil, reversibly inhibits dopamine-stimulated secretion. Ionophore A-23187 (2[(3.beta., 9.alpha., 11.beta.-trimethyl)-8-(2-pyrrolecarboxymethyl)-1-7-dioxyaspiro [6-6] undecyl-2.beta.-methyl]-5-methylaminobenzoxazole-4-carboxylic acid) is unable to induce glands to secrete. Studies in which labeled and unlabeled Ca2+ flux were measured indicate that catecholamines induce release of Ca from intracellular stores during secretion. Cyclic[c]AMP/theophylline-stimulated secretion is inhibited by verapamil and by the exclusion of Ca from the support medium. The primary catecholamine stimulus induces cAMP formation and mobilization of Ca2+ (intra- and extracellular). cAMP and Ca may interact to control secretion within the fluid transporting cells of types II and III alveoli.