Fy. Chueh et al., DL-TETRAHYDROPALMATINE-PRODUCED HYPOTENSION AND BRADYCARDIA IN RATS THROUGH THE INHIBITION OF CENTRAL NERVOUS DOPAMINERGIC MECHANISMS, Pharmacology, 51(4), 1995, pp. 237-244
The effects of DL-tetrahydropalmatine (THP; a main active substance of
the Chinese herb corydalis), haloperidol (a dopamine D-2 receptor ant
agonist), apomorphine and amphetamine on cardiovascular function and s
triatal dopamine (DA) release were compared in rats under general anes
thesia. Intravenous administration of THP (1-10 mg/kg) or haloperidol
(0.5-1.25 mg/kg) produced hypotension, bradycardia and increased DA re
lease in the striatum. On the other hand, amphetamine (0.5-1.25 mg/kg)
produced hypertension, tachycardia and increased striatal DA release.
However, intravenous injection of apomorphine (0.5-1.25 mg/kg) produc
ed hypotension, bradycardia and decreased striatal DA release. In addi
tion, the THP-induced hypotension was attenuated by pretreatment with
spinal transection or amphetamine, while the THP-induced bradycardia w
as attenuated by pretreatment with bilateral vagotomy or amphetamine.
Thus, it appears that THP acts through DA D-2 receptor antagonism to i
nduce hypotension and bradycardia in rats.