The purpose of this study was to compare ganglionic blockade with trimethaphan (TMP) and an alternative drug strategy using combined muscarinic antagonist (glycopyrrolate, GLY) and α-2 agonist (dexmedetomidine, DEX). Protocol 1: incremental phenylephrine was administered during control and combined GLY-DEX, or control and TMP on two control combined GLY and DEX or TMP infusion on two randomized days. Protocol 2: muscle sympathetic nerve activity (MSNA) and the baroreflex MSNA relationship was determined before and after GLY-DEX. Blood pressure was higher with GLY-DEX (99±3 mm Hg) and lower with TMP (78±3 mm Hg) relative to control (GLY-DEX: 90±2 mm Hg; TMP: 91±2 mm Hg;P<0.05). Incremental phenylephrine increased pressure during GLY-DEX (P<0.01 vs control) and TMP (P<0.01 vs control) to a similar degree. Both GLY-DEX and TMP infusion inhibited norepinephrine release (P<0.01 vs control). GLY-DEX inhibited baseline MSNA (P<0.05) and baroreflex changes in MSNA (P<0.01). We conclude that the GLY-DEX alternative drug strategy can be used as a reasonable alternative to pharmacologic ganglionic blockade to examine autonomic cardiovascular control.
ASJC Scopus subject areas
- Pharmacology (medical)