Interactions of lanatoside C and potassium on atrioventricular conduction in rabbits.
نویسندگان
چکیده
Intra-atrial, intranodal and His-Purkinje conduction times were determined in perfused rabbit hearts. In one series, the concentration of lanatoside C was increased by 0.4 mg/liter every 30 minutes, in the presence of normal (4.5) or high (7.5 DIM) K in the perfusion fluid. At high (K) the glycoside produced a greater increase in intra-atrial and His-Purkinje conduction times but caused a smaller increase of intranodal conduction time than at normal (K + ). Seconddegree A-V block always occurred intranodally, but the incidence was lower with high (K). In another series, (K + ) was increased by 3 MM every "30 minutes, in the absence or presence (0.4, 0.8 or 1.2 mg/liter) of lanatoside C No difference was seen between hearts treated with lanatoside C and those untreated at the level of (K) producing failure of conduction. At all levels of glycoside, conduction delay caused by high (K) was greatest within the atria, less in the His-Purldnje system and insignificant within the A-V node. Intra-atrial and His Purkinje block were observed but never an intranodal block. It is concluded that (1) cardiac glycoside and high (K) primarily affect different regions of the A-V conducting system, and (2) aggravation of glycoside-induced A-V block by high (K + ) may result from additional intraatrial and His-Purkinje block rather than from further depression of intranodal conduction. Electrophysiological mechanisms underlying these interactions were also discussed. ADDITIONAL
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ورودعنوان ژورنال:
- Circulation research
دوره 27 6 شماره
صفحات -
تاریخ انتشار 1970