FLUID SECRETION BY ISOLATED TICK SALIVARY-GLANDS DEPENDENT ON AN INTACT CYTOSKELETON

Isolated salivary glands from female Dermacentor variabilis (Say) were pre-treated with either cytochalasin D or nocodazol, followed by stim ulation with dopamine. Glands pre-treated with 1 muM-cytochalasin D di d not secrete fluid; pre-treatment with 1 nM-cytochalasin D did not si gnificantly reduce fluid secretion. Glands pre-treated with 1 muM-noco dazol had a significant reduction in fluid secretion (P = 0.003); 1 nM -nocodazol did not significantly affect fluid secretion. Ligation of t he main salivary duct and pre-treatment with 1 muM-cytochalasin D sign ificantly increased gland weight compared to the dopamine stimulated c ontrols (P = 0.0412). Cytochalasin D-treated type Ill acini had a sign ificantly larger mean diameter compared to the dopamine control (P = 0 .0047). Glands treated with 1 mM-verapamil plus 10 muM-dopamine exhibi ted a significant decrease in fluid secretion (P = 0.017), and when li gated, had a significantly decreased weight compared to the controls ( P = 0.0028).