The effect of dicyclomine hydrochloride, an anticholinergic agent, on heart rate variability and squatting test in healthy volunteers

Background and Squatting test and heart rate variability (HRV) are currently being used to evaluate cardiovascular autonomic nervous function. HRV indexes are able to measure vagal function, while squatting test is able to measure both sympathetic and vagal functions. Our objective in this research is to evaluate the influence of injective dicyclomine hydrochloride (DCH)-an M1 receptor selective antagonist- on autonomic nervous system function regarding HRV indexes and squatting test.Fifteen healthy males 19-24 year-old volunteers were involved in this single blind research. Each volunteer was referred two times every week and in each session the DCH (20 mg / 2ml) or placebo (2 ml) is injected to the muscle and between 30 to 40 minutes after injection, the uncontrolled normal breathing test and squatting test were conducted. After that, those parameters which show cardiac vagus and sympatic activity were measured in these tests.Administration of single dose of DCH didn’t cause any side effects; only one case of dry mouth is monitored. An increase in HRV indexes in uncontrolled normal breathing test, increase in vagal ratio, and decrease in sympathetic ratio in squatting test all caused by DCH.Although DCH is an anticholinergic agent, in muscular administration with 20 mg dose, regarding HRV parameters and squatting test, it shows cholinergic effects.