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Intracellular calcium and pacemaker ...

Li, Jin.

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Intracellular calcium and pacemaker activity in the sinoatrial node.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Intracellular calcium and pacemaker activity in the sinoatrial node./
Author:	Li, Jin.
Description:	103 p.
Notes:	Source: Dissertation Abstracts International, Volume: 57-11, Section: B, page: 6696.
Contained By:	Dissertation Abstracts International57-11B.
Subject:	Biology, Animal Physiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9711299
ISBN:	059118771X

Intracellular calcium and pacemaker activity in the sinoatrial node.
Li, Jin.

Intracellular calcium and pacemaker activity in the sinoatrial node. - 103 p.

Source: Dissertation Abstracts International, Volume: 57-11, Section: B, page: 6696.

Thesis (Ph.D.)--Texas Tech University, 1997.

The importance of the sinoatrial (S-A) node as the pacemaker of the heart is well known; however, little is known about calcium homeostasis and excitation-contraction coupling in the pacemaker cells. Thus, the major objectives of this dissertation research were: (1) to quantitatively measure intracellular calcium (Ca

ISBN: 059118771XSubjects--Topical Terms:

1017835
Biology, Animal Physiology.

Intracellular calcium and pacemaker activity in the sinoatrial node.
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020 $a 059118771X
035 $a (UnM)AAI9711299
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100 1 $a Li, Jin. $3 1297188
245 1 0 $a Intracellular calcium and pacemaker activity in the sinoatrial node.
300 $a 103 p.
500 $a Source: Dissertation Abstracts International, Volume: 57-11, Section: B, page: 6696.
500 $a Chairperson: Richard D. Nathan.
502 $a Thesis (Ph.D.)--Texas Tech University, 1997.
520 $a The importance of the sinoatrial (S-A) node as the pacemaker of the heart is well known; however, little is known about calcium homeostasis and excitation-contraction coupling in the pacemaker cells. Thus, the major objectives of this dissertation research were: (1) to quantitatively measure intracellular calcium (Ca $\ rm\sb{i}\sp{2+} $) in isolated pacemaker cells; (2) to examine the relationship between Ca $\ rm\sb{i}\sp{2+} $ and electrical activity; and (3) to measure Ca $\ sp{2+} $ release from the sarcoplasmic reticulum (SR) and determine its effect on pacemaker activity. We used the fluorescent Ca $\ sp{2+} $ indicator, Indo-1, to assess the changes in Ca $\ rm\sb{i}\sp{2+} $, and perforated-patch whole-cell recordings to monitor the electrical activity of single, cultured pacemaker cells that had been isolated from the rabbit S-A node. Indo-1 fluorescence ratios were calibrated both in vitro and in vivo. The contributions to action potential-induced Ca $\ rm\sb{i}\sp{2+} $ transients from Ca $\ sp{2+} $ entry through voltage-gated channels and Ca $\ sp{2+} $ release from the SK were demonstrated. The results indicate the existence of an internal Ca $\ sp{2+} $ store, the SR, and that action potential-induced Ca $\ rm\sb{i}\sp{2+} $ transients are produced mainly by Ca $\ sp{2+} $ entry through voltage-gated Ca $\ sp{2+} $ channels, rather than by Ca $\ sp{2+} $ release from the SR. Simultaneous recordings of membrane potentials and the Indo-1 fluorescence ratio showed that automaticity can be modified by isoproterenol and caffeine, agents that modulate Ca $\ rm\sb{i}\sp{2+} $. Changes in beat rate were correlated with changes in Ca $\ rm\sb{i}\sp{2+} $, however, Ca $\ rm\sb{i}\sp{2+} $ transients were not essential for cells to generate spontaneous firing. Using the perforated-patch voltage-clamp technique, we studied the effects of ryanodine and thapsigargin, inhibitors of SR Ca $\ sp{2+} $ release, on pacemaker activity, hyperpolarization-activated inward current, time-independent inward current, L- and T-type Ca $\ sp{2+} $ currents, and inward Na $\ sp{+} $- Ca $\ sp{2+} $ exchange current. Both ryanodine and thapsigargin slowed pacemaker activity significantly, in part by reducing inward Na $\ sp{+} $- Ca $\ sp{2+} $ exchange current; ryanodine also had a direct inhibitory effect on T-type Ca $\ sp{2+} $ current. In summary, rabbit S-A node pacemaker cells display a complex set of positive and negative feedback mechanisms that control intracellular Ca $\ sp{2+} $ and pacemaker activity.
590 $a School code: 0230.
650 4 $a Biology, Animal Physiology. $3 1017835
690 $a 0433
710 2 0 $a Texas Tech University. $3 1017459
773 0 $t Dissertation Abstracts International $g 57-11B.
790 1 0 $a Nathan, Richard D., $e advisor
790 $a 0230
791 $a Ph.D.
792 $a 1997
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9711299