Effects of alpha-methyldopa on the sympathetic nervous system activity in health participants

Abstract

Methyldopa (L-alpha-Methyl-3,4-dihydroxyphenylalanine) is a catecholamine used as an antihypertensive agent.1 Alpha-Methyldopa is not used as frequently anymore due to side effects, but it is still used especially in developing countries due to its low cost. Indications are mostly for the management of pregnancyinduced hypertension (PIH), as it is relatively safe in pregnancy compared to other antihypertensive drugs. This project is intended to increase the already-existing knowledge base of the mechanism of pharmacological action and to stimulate further investigation through research. The sympathetic nervous system is a division of the autonomic nervous system and it is responsible for the “flight-or-fight” response. It is involuntary and constantly active to maintain homeostasis in the human body. Sympathetic responses include an increase in heart rate, blood pressure and cardiac output, dilation of pupils and bronchioles, constriction of blood vessels, contraction of sphincters and inhibition of gut motility and secretions. The purpose of this study is to evaluate the activity of the sympathetic nervous system of volunteers by three different techniques (QT interval and Heart rate variability and Skin conductance) after a week of a bi-daily dosage of alphamethyldopa. All volunteers received either 250mg alpha-methyldopa orally or a placebo tablet in a randomized, double blind, placebo controlled study design. The correlation between the following techniques was also evaluated: Skin conductance as measured by the ProComp Infiniti Biofeedback apparatus, QT interval on ECG and HRV measured with Viport apparatus. A salivary sample was collected to evaluate the effect of alpha-methyldopa on salivary cortisol using an ELISA kit for analysis.