Effect of parasympathetic denervation on K+ release by rat parotid slices.

1. By measuring the release of 86Rb, potassium movement was compared in parasympathectomized (Px) and contralateral control parotid gland slices three weeks following surgical denervation. 2. Carbachol and phenylephrine elicited a biphasic increase in 86Rb release that was dose related and could be blocked by atropine and phentolamine respectively. The transient phase was of 2-4 min duration and Ca independent whereas the sustained phase of 86Rb release was greatly reduced by the omission of the external Ca. 3. Denervation caused a shift to the left of the 86Rb efflux dose-response curve to carbachol and phenylephrine (3.75- and 3.37-fold respectively). Pilocarpine had similar action to carbachol but it behaved as a partial agonist. 4. Parasympathectomy (Px) increased the intrinsic activity of the partial agonist pilocarpine and converted it to a full agonist. Results of the present study indicate the possibility of an altered receptor-signal transduction mechanism between the receptor and phospholipid turnover/Ca mobilization in the denervated rat parotid gland.