T. Taesotikul et al., CARDIOVASCULAR ACTIVITY OF THE CRUDE ALKALOIDAL FRACTION FROM TABERNAEMONTANA-PANDACAQUI IN THE RAT, Journal of ethnopharmacology, 59(3), 1998, pp. 131-137
The effects of a crude alkaloidal (CA) fraction from the stem of Taber
naemontana pandacaqui Poir. on the blood pressure and heart rate were
investigated in conscious as well as anesthetized rats. The CA fractio
n exerted a hypotensive activity in both experimental models. In pento
barbital anesthetized rats, an intravenous administration of the CA fr
action caused two consecutive hypotensive and bradycardiac responses.
In order to investigate the mechanism of the responses, the effect of
the CA fraction on the blood pressure and the heart rate was tested in
various experimental animals such as pithed rats, reserpinized rats u
nder pentobarbital anesthesia and atropine-or chlorpheniramine-treated
rats under pentobarbital anesthesia. The results obtained suggest tha
t the hypotensive and bradycardiac responses of the first phase might
involve cholinergic and central mechanisms, whereas those of the secon
d phase involve mechanisms which are mediated by central, biogenic ami
nes, acetylcholine and histamine. (C) 1998 Elsevier Science Ireland Lt
d.