The intrinsic cycle length in small pieces isolated from the rabbit sinoatrial node.

In this study we show that small pieces of tissue cut from the intact sinoatrial node beat faster, but with the same regularity as the intact sinoatrial node. The pieces with highest diastolic depolarization rate are not isolated from the primary pacemaker area, but from sites closer to the crista terminalis. In pieces cut from the primary pacemaker area, changes in the action potential configuration are restricted to the action potential duration, whereas in pieces cut from sites closer to the crista terminalis, not only the action potential duration has decreased, but also the diastolic depolarization rate has increased. Under the influence of adrenaline or acetylcholine, quiescent pieces are able to generate spontaneous activity.

[1]  D. J. Howell,et al.  Heart Rate of Female Big Brown Bats in Flight , 1969 .

[2]  F. I. Bonke,et al.  Change of Cardiac Rhythm in the Rabbit after an Atrial Premature Beat , 1969, Circulation research.

[3]  H. Jongsma,et al.  The establishment of regular beating in populations of pacemaker heart cells. A study with tissue-cultured rat heart cells. , 1983, Journal of molecular and cellular cardiology.

[4]  H. Brown.  Electrophysiology of the sinoatrial node. , 1982, Physiological reviews.

[5]  H. Jongsma,et al.  Interaction of Adrenaline and Acetylcholine on Sinus Node Function , 1982 .

[6]  H. Jongsma,et al.  Interaction of adrenaline and acetylcholine on cardiac pacemaker function. Functional inhomogeneity of the rabbit sinus node. , 1980, The Journal of pharmacology and experimental therapeutics.

[7]  H. Jongsma,et al.  Functional and morphological organization of the guinea-pig sinoatrial node compared with the rabbit sinoatrial node. , 1985, Journal of molecular and cellular cardiology.

[8]  D. Glomset,et al.  A morphologic study of the cardiac conduction system in ungulates, dog, and man: Part I: The sinoatrial node , 1940 .

[9]  A E Becker,et al.  Functional and Morphological Organization of the Rabbit Sinus Node , 1980, Circulation research.

[10]  G H Pollack,et al.  Threshold effects of acetylcholine on primary pacemaker cells of the rabbit sino-atrial node , 1985, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[11]  F. Davies,et al.  The conduction of the impulse for cardiac contraction. , 1952, Journal of anatomy.

[12]  H. Jongsma,et al.  Cycle length dependence of the chronotropic effects of adrenaline and acetylcholine in the rabbit sinoatrial node. , 1983, Journal of the autonomic nervous system.

[13]  B. Slinker,et al.  Arterial baroreflex control of heart rate in the horse, pig, and calf. , 1982, American journal of veterinary research.

[14]  H. Brown,et al.  The Relative Contributions of Various Time-Dependent Membrane Currents to Pacemaker Activity in the Sino Atrial Node , 1982 .

[15]  T. N. James,et al.  The sinus node. , 1977, The American journal of cardiology.

[16]  Two electrophysiologically distinct types of cultured pacemaker cells from rabbit sinoatrial node. , 1986, The American journal of physiology.

[17]  H. Jongsma,et al.  Cycle length dependence of the chronotropic effects of adrenaline, acetylcholine, Ca2+ and Mg2+ in the Guinea-pig sinoatrial node. , 1984, Journal of the autonomic nervous system.

[18]  D. DiFrancesco.  The cardiac hyperpolarizing-activated current, if. Origins and developments. , 1985, Progress in biophysics and molecular biology.

[19]  L. Mcewen,et al.  The effect on the isolated rabbit heart of vagal stimulation and its modification by cocaine, hexamethonium and ouabain , 1956, The Journal of physiology.

[20]  C. Brooks,et al.  The sinoatrial pacemaker of the heart , 1972 .