کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6004763 1579561 2009 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Tertiapin-Q removes a large and rapidly acting component of vagal slowing of the guinea-pig cardiac pacemaker
موضوعات مرتبط
علوم زیستی و بیوفناوری علم عصب شناسی علوم اعصاب سلولی و مولکولی
پیش نمایش صفحه اول مقاله
Tertiapin-Q removes a large and rapidly acting component of vagal slowing of the guinea-pig cardiac pacemaker
چکیده انگلیسی

The participation of acetylcholine-activated potassium current (IK,ACh) and hyperpolarization-activated pacemaker current (If) in vagal bradycardia were examined using vagally-innervated preparations of guinea-pig atria. Preparations were maintained in Krebs-Henseleit solution (36 °C). Before treatment, trains of vagal stimuli (10 s at 2, 5 and 10 Hz) produced graded bradycardias displaying rapid onset and offset. Tertiapin-Q (300 nM), which blocks IK,ACh, had no effect on baseline atrial rate. In tertiapin-Q, vagal bradycardia displayed a gradual onset and offset, with a peak response ~ 50% of that recorded in control conditions. Cumulative addition of 1 mM ZD7288 (blocker of If) caused atrial rate to fall by ~ 60%, but had no further effect on the amplitude of the vagal bradycardia, while response onset and offset became slightly faster. From these observations, we argue that (i) vagal bradycardia was attributable primarily to activation of IK,ACh, (ii) vagal modulation of If had a minor influence on the rate of onset and offset of bradycardia, and (iii) removal of the influence of IK,ACh unmasked a slow response, of undetermined origin, to vagal stimulation. In a separate set of experiments we compared the effects of 1 mM Ba2+ and 300 nM tertiapin-Q on vagal bradycardia. Ba2+ reduced baseline atrial rate and the response to vagal stimulation. Subsequent cumulative addition of tertiapin-Q had no additional effect on baseline atrial rate, but caused further reduction in the amplitude of vagal bradycardia, suggesting that 1 mM Ba2+ did not achieve a complete block of IK,ACh in this preparation.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Autonomic Neuroscience - Volume 150, Issues 1–2, 5 October 2009, Pages 76-81
نویسندگان
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