Modification of blood pressure and nictitating membrane response to sympathetic amines by selective monoamine oxidase inhibitors, types A and B, in the cat.

The selective monoamine oxidase (MAO) inhibitors clorgyline, selegiline and AGN 1135 did not cause a change in responses of the cat nictitating membrane to preganglionic sympathetic nerve stimulation at 5 Hz. Both selective MAO-A and MAO-B inhibitors markedly potentiated nictitating membrane contractions in response to beta-phenylethylamine (PEA). However, the responses to tyramine were unchanged. The pressor responses to tyramine were potentiated by the selective MAO-A inhibitor clorgyline (2 mg kg-1) but not by selegiline (1.0 mg kg-1) and AGN 1135 (1.5 mg kg-1), selective MAO-B inhibitors. At the doses used selegiline and AGN 1135 caused a near total selective inhibition of liver and brain MAO-B, while clorgyline inhibited MAO-A only in the brain. AGN 1135, like selegiline, could be a useful drug in potentiating the action of L-DOPA in Parkinson's disease.