Effects of atropine on contraction of rabbit aortic smooth muscle and cell proliferation
Chen, J.M.; Zhang, M.Z.; Gu, S.L.; Zhang, G.Y.
Yao Xue Xue Bao 28(4): 246-250
1993
ISSN/ISBN: 0513-4870 PMID: 8213165 Document Number: 412650
The calcium antagonistic actions of atropine (Atr) and verapamil (Ver) were studied on the contraction of rabbit thoracic aorta strips induced by CaCl-2 and KCl. Both Atr and Ver were found to depress the contraction as demonstrated by the shift- to- right of the dose-effect relationship curves and the decrease of maximal responses, with the value of pD'2 being 4.4 and 5.8 respectively. The intracellular Ca-2+-dependent component of NE-induced aortic strip contraction was also inhibited by the 2 drugs, but the extracellular Ca-2+-dependent component was barely or not inhibited by Atr before its concentration was raised to 100 mu-mol/L. These results indicate that the depressive effect of Atr on aortic contraction is mainly exerted by acting on the PDC (potential-dependent channel). The action of Atr on proliferation of cells was also studied in rabbit aortic smooth muscle cell (ASMC) culture. The growth was inhibited by Atr when Ca-2+ was present in the medium. When Ca-2+ was absent, however, the growth was stimulated by Atr 20.6 apprx 185.2 mu-mol/L, but inhibited by Atr 55.7 apprx 166.7 mu-mol/L, suggesting that ca-2+ is somehow involved in the action of Atr on ASMC growth.