Cholinergic stimulation with pyridostigmine improves autonomic function in infarcted rats

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Research
• Pharmacology

Background:

• Myocardial infarction (MI) often leads to impaired left ventricular (LV) and autonomic dysfunction.
• Autonomic markers post-MI have significant prognostic implications.
• Pyridostigmine bromide is an acetylcholinesterase inhibitor with potential effects on autonomic tone.

Purpose of the Study:

• To evaluate the effects of early, short-term pyridostigmine bromide treatment on LV and autonomic functions following MI in rats.
• To investigate the impact of pyridostigmine on baroreflex sensitivity (BRS) and heart rate variability (HRV) post-MI.

Main Methods:

• Male Wistar rats were assigned to control, pyridostigmine, infarcted, and infarcted + pyridostigmine groups.
• Pyridostigmine bromide was administered in drinking water for 11 days, starting immediately after MI or sham operation.
• Left ventricular function was assessed via echocardiography and LV catheterization; autonomic control was evaluated using BRS, HRV, and pharmacological blockade.

Main Results:

• Pyridostigmine treatment reduced infarct size and prevented impairment of +dP/dT in infarcted rats.
• Mean blood pressure was restored in the pyridostigmine-treated infarcted group compared to the untreated infarcted group.
• Pyridostigmine significantly improved BRS and HRV, indicated by enhanced tachycardic/bradycardic responses and a reduced LF/HF ratio, suggesting increased vagal and reduced sympathetic tone.

Conclusions:

• Early, short-term pyridostigmine bromide treatment improves autonomic function, including BRS and HRV, in a rat model of MI.
• The observed improvements are likely due to enhanced parasympathetic and reduced sympathetic tone.
• These findings suggest potential clinical applications of pyridostigmine in managing post-MI autonomic dysfunction.