EFFECT OF L-DOPA ON BLOOD PRESSURE AND SYMPATHETIC NERVE ACTIVITY AFTER DECARBOXYLASE INHIBITION IN CATS

¹ Departments of Pharmacology and Physiology, Indiana University School of Medicine,Indianapolis, Indiana and Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland

Blood pressure, heart rate and electrical activity of preganglionic splanchnic sympathetic nerves and postganglionic renal and cardiac sympathetic nerves were measured in cats given L-dopa after pretreatment with a peripheral decarboxylase inhibitor. L-Dopa caused a reduction in pre- and postganglionic sympathetic nerve activity which closely paralleled the fall in blood pressure and heart rate. L-Dopa, when given with a decarboxylase inhibitor, reduces sympathetic nerve activity through an effect on the central nervous system. This is a mechanism by which L-dopa lowers blood pressure in anesthetized cats.