Characteristics of the rectifying properties of the sino‐atrial node cell of the rabbit.

Abstract

After confirming the region of the sino-atrial (S-A) node by its characteristic action potential, man-made strands including the pacemaker region of the rabbit heart were prepared and simple cable theory analysis performed. The estimated .lambda. was 828 .mu.m in Tyrode. The single sucrose gap method conducted both the current-clamp experiment and the voltage-clamp experiment. In both methods outward-going and inward-going rectification were observed. The existence of a positive after-potential in the case of the current-clamp experiment and an outward current tail in the base of the voltage-clamp experiment after cessation of cathodal pulses suggests that the outward-going rectification is due to the increase of K conductance. The slowly developed inward-going rectification was always accompanied with a decrease of membrane resistance. It is unlikely that change in K conductance is solely responsible for this rectification. Changes in both Na and Cl conductance together with K conductance might be involved.