[Calcium antagonistic effect of Xanthotoxol on isolated guinea pig atria].
OBJECTIVE
To study the mechanism of depressant effect of xanthotoxol (XT) on contractility in the isolated guinea pig atria.


METHODS
The contractile force of the isolated left atria was determined by tension recording method.


RESULTS
In the experiments on contractility of the left atria XT and Verapamil (Ver) significantly depressed the positive staircase phenomena, which was reversed by Ver but not by XT. However, the post-rest potentiation of myocardial contraction in the left atria was only markedly decreased by XT but not by Ver. Furthermore, XT not only attenuated the positive inotropic action, but also delayed the following toxicity response induced by ouabain in the isolated left atria.


CONCLUSIONS
XT blocked not only the voltage dependent calcium channel, but also the receptor operated calcium channel in the isolated guinea pig atria.
Liu
Jianxin
J
Department of Pharmacology, Gannan Medical College, Ganzhou 341000.
Lian
Qishen
Q
Zhou
Li
L
Zhou
Qing
Q
He
Wei
W
Zhu
Zunping
Z
Lai
Fei
F
D000818:Animals; D019661:Apiaceae / Q000737:chemistry*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D005260:Female; D011564:Furocoumarins / Q000494:pharmacology*; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010946:Plants, Medicinal / Q000737:chemistry*; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004365:Drugs, Chinese Herbal; D011564:Furocoumarins; C021768:xanthotoxol; D014700:Verapamil