Voltage-gated sodium channel function from neonatal and adult rat cardiomyocytes was measured and compared. Channels from neonatal ventricles required an approximately 10 mV greater depolarization for voltage-dependent gating events than did channels from neonatal atria and adult atria and ventricles. We questioned whether such gating shifts were due to developmental and/or chamber-dependent ch...

Tetrodotoxin (TTX) at a concentration of 1.6 X 10"M blocked intracellularly recorded action potentials in 12and 18-day-old embryonic chick atria. However, TTX, 1 X K H M , did not abolish action potentials recorded from cells in 6-day-old atria. TTX-sensitive receptor sites were present in 6-day-old atrial membranes because the toxin depressed the early Na conductance that generated the rapid d...

The collagen concentrations of the four cardiac chambers of normal hearts were determined chemically. Right ventricles and atria contained significantly higher collagen concentrations than did left ventricles and atria. The atria contained twice the collagen concentration of the ventricles. Severe atherosclerosis, hypertrophy and coronary occlusion did not necessarily increase the concentration...

To assess the influence of the autonomic nervous system upon the recovery of the normal human sinus node, the responses to overdrive pacing at multiple cycle lengths of the denervated donor heart sinus nodes of 18 human cardiac transplant recipients were compared to the responses of those 18 patients' innervated, remnant atria and of 20 control subjects with normal sinus node function. The mean...

To assess the influence of the autonomic nervous system upon the recovery of the normal human sinus node, the responses to overdrive pacing at multiple cycle lengths of the denervated donor heart sinus nodes of 18 human cardiac transplant recipients were compared to the responses of those 18 patients' innervated, remnant atria and of 20 control subjects with normal sinus node function. The mean...

Effects of ouabain and catecholamines_ and their modifications_ by propranolol were investigat ed on the functional refractory period ( FRP ), contractile force and heart rate in isolated atria of guinea-pigs_ and rats.. Catecholamines produced a transient decrease in the FRP of guinea-pig atria, while ouabain caused a continual increase after a latent period of 5 to 10 minutes. The FRP in rat ...

BACKGROUND More accurate and reliable stroke risk prediction tools are needed to optimize anticoagulation decision making in patients with atrial fibrillation (AF). We developed a new AF stroke prediction model using the original Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) AF cohort and externally validated the score in a separate, contemporary, community-based inception AF ...

Isolated specimens of right atrial appendage from 138 subjects with atrial disease or dysfunction and from seven subjects with clinically normal atria were examined electrophysiologically by conventional microelectrode techniques. The endocardial surfaces of diseased atrial appendage were found to be characterized primarily by cells with diastolic transmembrane potentials of — 56 ± 0.7 (SEM) mV...

The potential functional roles of M(3) muscarinic receptors in mouse atria were examined by pharmacological and molecular biological techniques, using wild-type mice, muscarinic M(2) or M(3) receptor single knockout (M(2)KO, M(3)KO), and M(2) and M(3) muscarinic receptor double knockout mice (M(2)/M(3)KO). Real-time quantitative reverse transcriptase-polymerase chain reaction analysis showed th...

Although diabetes has been identified as a major risk factor for atrial fibrillation, little is known about glucose metabolism in the healthy and diabetic atria. Glucose transport into the cell, the rate-limiting step of glucose utilization, is regulated by the Glucose Transporters (GLUTs). Although GLUT4 is the major isoform in the heart, GLUT8 has recently emerged as a novel cardiac isoform. ...