FK-KMK UGM. Faculty of Medicine, Public Health, and Nursing (FK-KMK) UGM held a Guest Lecture on Friday (28/7) in the Auditorium, 1st Floor, Tahir Postgraduate Building. The speaker in this Guest Lecture is Dr. Robert G. Carroll, Ph.D from East Carolina University School of Medicine, Greenville USA with the theme “Calcium Homeostasis in the Heart”.

Myocardial cells, notably the pacemaker cells of the sinoatrial node and atrioventricular node, will spontaneously depolarize to threshold, initiating an action potential (automaticity). The early depolarization is mediated by the hyperpolarization induced opening of K channels and closing of Na channels.

“Researchers called this a funny current because the other voltage gated channels are closed by hyperpolarization,” Carroll added. The later stages of this spontaneous depolarization are mediated by L-type calcium channels.

Fast heart rate causes increased contractility, meanwhile early extrasystole causes decreased contractility. Studies with papillary muscle show weaker contraction with faster pacing. “If the data does not agree with the theory, first check the data, if the data are valid, change the theory,” Carroll explained. (Reporter: Nirwana)