AJP - Regulatory, Integrative and Comparative Physiology, Vol 235, Issue 1 76-R81, Copyright © 1978 by American Physiological Society
Actions of some transmitters and their antagonists on salivary secretion in a tick
W. R. Kaufman
Cholinomimetics (pilocarpine, carbachol, physostigmine, acetylcholine,
acetyl-beta-methylcholine) and sympathomimetics (dopamine, epinephrine),
when injected into the hemolymph, provoked salivary fluid secretion in the
female ixodid tick Amblyomma hebraeum Koch. Atropine, but not tubocurarine
or toxiferine, abolished pilocarpine-induced secretion without reducing the
response to dopamine. Reserpine and guanethidine likewise selectively
attenuated pilocarpine-induced secretion. Following extirpation of the
synganglion, pilocarpine no longer provoked a secretory response whereas
dopamine did. Thus, the salivary gland appears to be innervated directly by
catecholaminergic rather than cholinergic secretory nerves. It is suggested
that pilocarpine elicits salivation by interacting with muscarinic-type
cholinergic receptors situated either on the cell bodies of the secretory
nerves, or alternatively in the integrative or sensory pathway.
