AUTONOMIC POSTGANGLIONIC INNERVATION OF THE NICTITATING MEMBRANE OF THE CAT

¹ Department of Pharmacology, School of Medicine, University of Washington, Seattle 5, Washington

A pharmacologic study of the innervation of nictitating membrane of the cat was approached in three ways: (1) innervatetl in situ preparation, (2) denervated in situ preparation, (3) the in vitro preparation.

The innervated membrane was excited to contract by postgangliouiic electrical stimulation of the cervical sympathetic and by humoral stimulation following intravenous injection of appropriate drugs. The denervated and isolated preparations were excited through humoral stimulation alone.

Methylatropine increased the electrical and adrenergic responses of the smooth muscle of the nietitating membrane in the innervated in situ preparation and adrenergic pharmacologic responses in the in vitro preparation, but caused a slight reduction in the pharmacologic adrenergic responses of the denervated in situ preparation.

Atropine reduced all the responses of the smooth muscle of the nietitating membrane in the three preparations studied.

Eserine potentiation was studied in the in vitro preparation and the implications of the results obtained were discussed.

The results of this investigation indicate that atrophic inhibition and eserine potentiation of contraction of the nictitating membrane of the cat are of a nonspecific nature, and provide no basis for the support of the hypothesis that there is a cholinergic mechanism in the innervation of the nictitating membrane of the cat.