토끼 심장 유두근에 대한 a, Cs 이온의 영향

Abstract

Actions of Ba" and Cs" upon the electrical activity were studied in isolated rabbit papillary muscles. All experiments were performed in Tris-buffered Tyrode solution which was aerated with 100% 02 and kept at 35°C. The results obtained were as follows: 1. Ba' (lmM) induced spontaneous activity on papillary muscle in an all-ot-none pattern. Above the concentration of 8mM Ba", plateau phase of action potential was remarkably prolonged. 2. Even in Ca" -free media, Ba' induced action potential with a long-lasting plateau phase and in accordance with the prolonged plateau phase, contraction curves could he divided into phasic and tonic components. 3. In the preparations activated by 2mM Ba*, noradrenaline (Zmg/L) promoted electrical activity, but Sooner made the activities change into fibrillation pattern. And bizarre extraspike appeared during the recovery phase from the Ba*-induced spontaneous activities by normal Tyrode in noradrenallne-treated preparation. 4. Bar-Induced spontaneous activities were inhibited by 24mM K+. 5. Cs" (20mM) made membrane potential hypopolarized, but did not induce spontaneous activities. And overshoot amplitude of action potential driven by electrical stimulation was decreased by Cs", 6. Cs" hardly influenced upon the Ba*-induced spontaneous activities.