SUPERSENSITIVITY OF THE NICTITATING MEMBRANE TO 5-HYDROXYTRYPTAMINE AND NOREPINEPHRINE AFTER VARIOUS PROCEDURES

¹ Pharmacological Research Unit, Council of Scientific and Industrial Research and the Department of Pharmacology, Medical College, Baroda, India

Denervation, decentralization and cocaine treatment of the dog nictitatung membrane increased its sensitivity to 5-hydroxytryptamune (5-HT) by about 10-fold. Cocaine treatment of the denervated dog membrane further enhanced its sensitivity to 5-HT. Denervation, decentralization and cocaine treatment increased the sensitivity of dog nictitating membrane to norepinephrine (NE) by 60-fold, 10-fold and 10-fold, respectively. Cocaine treatment of the decentralized dog membrane further enhanced its sensitivity to NE. Time courses of development of supersensitivity of the denervated cat nictitatung membrane to 5-HT and NE were identical. The time courses of decentralization supersensitivity to 5-HT and NE were also fairly similar. Supersensitivity of the nictitating membrane to 5-HT may be due to an impairment of its uptake at the adrenergic nerve terminals as well as to the changes occurring on the postsynaptic membrane after various procedures.