Mean arterial pressure (MAP) changes after intravenous injection of arecoline. No significant differences were observed among groups (0.06, 0.2 and 0.6 mg/kg of arecoline) in the pre-test, but a remarkable decrease was observed in Period 1 followed by a marked increase in Period 2, after intravenous arecoline treatments. *P < 0.05; **P < 0.01.