| Summary: | Birds acquired endothermy and four-chambered heart independently from mammals in the course of evolution. Though avian embryos are widely used in experiments, little is known about adult avian heart. Recent studies have shown that despite of big evolutionary distance, the set of repolarizing potassium currents in avian myocardium resembles that in mammalian heart as well as in humans. That allows to propose birds as a potential model in experimental cardiology. The present study for the first time describes inward rectifier potassium currents in working myocardium of quail. Using patch clamp method, we recorded main background inward rectifier current IK1 in isolated atrial and ventricular cardiomyocytes of quail. Both inward and outward components of IK1 in ventricular cells were larger than those in atrial cells, while there were no differences in voltage dependence of inward rectification. Acetylcholine and carbachol induced activation of acetylcholine-dependent inward rectifier current IKACh in atrial, but not in ventricular myocytes. IKACh in atrial myocytes was sensitive to tertiapin. Constitutively active IKACh has not been detected. In multicellular preparations of quail right atrium carbachol induced hyperpolarization and shortening of action potentials, while in preparations of right ventricle no such effects were observed. Activation of IKACh upon application of carbachol was dose-dependent with EC50=4,922∙10-7М. The described distribution of inward rectifier currents in avian myocardium is similar to that in mammalian species, which are widely used as model objects in experimental cardiology. Несмотря на то, что эмбрионы птиц широко используются в исследованиях, клеточные и молекулярные аспекты физиологии сердца взрослых птиц изучены слабо. Недавние исследования показали, что, несмотря на отдаленное систематическое положение, набор реполяризующих калиевых токов в сердце птиц напоминает таковой у млекопитающих и, в частности, у человека, что позволяет считать птиц потенциальным модельным объектом в ...
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