Postrest Shortening of the Action Potential Duration in Rabbits
| Autor: | Mikiko Nakagawa, Naohiko Takahashi, Takao Fujino, Hidetoshi Yonemochi, Shuji Ishida, Morio Ito, Tetsu Iwao, Tetsunori Saikawa |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Male
medicine.medical_specialty Potassium Channels Time Factors Physiology Heart Ventricles Action Potentials Blood Pressure Potassium Channels Tandem Pore Domain Heart Rate Internal medicine Potassium Channel Blockers medicine Animals Ventricular Function 4-Aminopyridine Papillary muscle Cardiac transient outward potassium current Ion Transport Ryanodine Chemistry Ryanodine receptor Cardiac Pacing Artificial Ryanodine Receptor Calcium Release Channel Vagus Nerve Papillary Muscles Potassium channel Sarcoplasmic Reticulum Electrophysiology medicine.anatomical_structure Endocrinology Ventricle Circulatory system Potassium Calcium Rabbits Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | Japanese Circulation Journal. 62:443-448 |
| ISSN: | 1347-4839 0047-1828 |
| DOI: | 10.1253/jcj.62.443 |
| Popis: | Previous evidence has shown that the action potential duration of rabbit ventricular muscle cells shortens after a rest period (postrest shortening). However, there has not been much research on postrest shortening in the intact heart. We recorded transmembrane action potentials (TAPs) of isolated papillary muscle from rabbit ventricle with glass microelectrodes and monophasic action potentials (MAPs) of the rabbit left ventricular endocardium with contact electrodes. In the in vitro experiments, repetitive regular stimuli (S1) at a cycle length of 1 sec were followed by a single extrastimulus (S2) at coupling intervals (S1S2) ranging between 0.5 sec and 8 sec. The increase in the S1S2 interval resulted in a progressive shortening of the duration of TAP elicited by the S2, which was abolished by the simultaneous application of 1 mmol/L 4-aminopyridine and 2 micromol/L ryanodine. In the in vivo experiments, regular right ventricular pacing (S1) at a cycle length of 0.35 sec was followed by a single extrastimulus (S2) with coupling intervals (S1S2) ranging between 0.25 sec and 3 sec. The increase in the S1S2 interval also resulted in a progressive shortening of the duration of MAP elicited by the S2. This is the first report to demonstrate postrest shortening in the intact heart, which probably occurs because of a mechanism analogous to that observed in the isolated ventricular muscle. |
| Databáze: | OpenAIRE |
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