硫氮䓬酮（Ro11 - 1781）和维拉帕米对兔心肌的负性肌力作用。

Negative inotropic effects of tiapamil (Ro11-1781) and verapamil in rabbit myocardium.

作者信息

Harada S, Sada H, Kojima M, Ban T

出版信息

Eur J Pharmacol. 1982 Feb 19;78(1):7-14. doi: 10.1016/0014-2999(82)90366-1.

Abstract

The effects of tiapamil (Ro11-1781) and verapamil on contractility were studied at 1 Hz in isolated rabbit left atrium and right ventricular papillary muscle. The ED50 of tiapamil for the depression of contractility was 33 and 18 times higher than that of verapamil in the former and latter tissue, respectively. In the presence of 100 microM of tiapamil or 10 microM verapamil, the positive staircase phenomenon in papillary muscle was reversed to a negative one. Also, the depression of contractility tended to be less in the first and second responses after a longer interruption of driving stimuli. Both drugs antagonized the inotropic effects of Ca2+ competitively and the pA2 for tiapamil was less than that for verapamil by 1.01. The potency ratios of tiapamil to verapamil for the contractility in this study correspond roughly with those found in clinical use.

摘要

在离体兔左心房和右心室乳头肌中，以1Hz的频率研究了替帕米（Ro11 - 1781）和维拉帕米对收缩性的影响。在上述两种组织中，替帕米抑制收缩性的半数有效剂量（ED50）分别比维拉帕米高33倍和18倍。在存在100微摩尔/升替帕米或10微摩尔/升维拉帕米的情况下，乳头肌中的正阶梯现象转变为负阶梯现象。此外，在驱动刺激长时间中断后的第一和第二次反应中，收缩性的抑制往往较小。两种药物均竞争性拮抗Ca2+的变力作用，替帕米的亲和力指数（pA2）比维拉帕米小1.01。本研究中替帕米与维拉帕米对收缩性的效价比大致与临床应用中的情况相符。