THE USE OF SERIAL CAROTID OCCLUSION, NICTITATING MEMBRANE AND CROSS-CIRCULATION TECHNICS IN THE INVESTIGATION OF THE CENTRAL HYPOTENSIVE ACTIVITY OF GANGLIONIC BLOCKING AGENTS

¹ Pharmacology Section, Sterling-Winthrop Research Institute, Rensselaer, New York

The effects of TEA, hexamethonium and Pendiomide were compared by the serial carotid occlusion response in the dog, nictitating membrane preparation in the dog and cat, and the cross-circulation experiment in the dog.

1. The potency of hexamethonium was found to be twice that of Pendiomide by the serial carotid occlusion response and the nictitating membrane preparation in both the cat and dog; four times as active as TEA by the serial carotid occlusion response, live times as active by the nictitating membrane in the cat and forty times as active by the nictitating membrane preparation in the dog.

2. The activity of TEA by the serial carotid occlusion response was approximately ten times as great as that measured at the superior cervical ganglion in the dog whereas no differences were observed in the activity of either hexamethonium on Pendiomide by these two test procedures.

3. The hypotensive activity of TEA in the dog was greater than that observed with Pendiomide or hexamethonium.

4. TEA was found to be equally as active as hexamethonium and Pendiomide in causing a centrally mediated hypotensive effect in the body of the recipient dog in the cross-circulation experiment.

5. A central and a peripheral sympathetic inhibitory mechanism appears to be equally involved in the hypotension produced by TEA whereas the peripheral component of action seems to predominate with hexamethonium and Pendiomide.

6. The use of the serial carotid occlusion response as a measure of central hypotensive activity was discussed.