To investigate the channels and neurotransmitters in the ventrolateral medulla (VLM) oblongata that are responsible for the maintenance of sympathetic tone and cardio-respiratory reflex regulation. Microinjections of excitant amino acid (glutamate, 100 nl, 100 mM), calcium channel blockers, agonists and antagonists were made throughout the VLM in anaesthetized rats. Arterial blood pressure, sym...