Role of brain amine transmitters and some neuromodulators in blood pressure, heart rate, and baroreflex control

Abstract

We studied the acute effects of transmitter release induced by intracisternal (i.c.) 6-hydroxydopamine (6-OHDA) from mainly noradrenergic (NA) neurons and by 5,6-dihydroxytryptamine (5,6-DHT) from serotonergic (5HT) neurons. Each group of neurons affects blood pressure and heart rate in conscious rabbits through both suprapontine and bulbospinal pathways that alter both sympathetic and vagal function. Some of the pathways are complex with 5HT neurons and NA neurons in series with one another, while in others a given autonomic function is altered through parallel independent mechanisms. The central effects of α-methyldopa and clonidine on blood pressure and heart rate are mediated through bot..