Arecoline induces dual modulation of blood pressure in rat, including an initial downregulation and a subsequent upregulation

Purpose: To determine the role of arecoline in cardiovascular modulation in rats.Methods: After rats were anaesthetized with intraperitoneal urethane (1.4 g/kg body weight), saline or arecoline (at doses of 1.0, 3.0 and 10.0 mg/kg) was intraperitoneally administered, and blood pressure (BP) was continuously recorded using a physiological apparatus. Mean arterial pressure (MAP), maximum changes in MAP and reaction time due to arecoline stimulations were calculated and analyzed.Results: Arecoline induced biphasic modulation in BP, including an initial downregulation followed by a subsequent upregulation. The MAP and maximum change in MAP exhibited a concentration-dependent effect in the downregulation phase (p < 0.001 within each group), but not in the upregulation phase (p > 0.05 within each group), while BP reaction time showed a dose-dependent prolongation in both downregulation and upregulation phases (ps < 0.01 within each group). Remarkably, arecoline-induced BP downregulation more rapidly and drastically than upregulation in each arecoline group.Conclusion: These results indicate that arecoline exerts a complex effect in cardiovascular modulation that should be considered as side effects in the clinical use of arecoline and/or with the habitual chewing of areca nuts. Keywords: Arecoline, Blood pressure, Downregulation, Upregulation