title: Age-related peculiarities of adrenergic regulation of cardiac chronotropic action after I f blockage.
abstract: The effects of norepinephrine on the heart rate were studied in 1-, 3-, 6-, and 20-week-old rats before and after blockade of hyperpolarization-activated currents (I f , I h ). In animals with mature sympathetic regulation of cardiac activity (6- and 20-week-old animals), I f blockage decreased the severity of norepinephrine-induced tachycardia. In newborn rats lacking sympathetic innervation of the heart, norepinephrine only slightly affected heart rate before and after I f blockage. In 3-week-old animals, I f blockage after norepinephrine pretreatment increased tachycardia.
authors: Department of Anatomy, Physiology, and Human Health Protection, Kazan' (Privolzhskii) State University, Russia. zefirovtl@mail.ru.
authors: N I
authors: NI
authors: Ziyatdinova
authors: R E
authors: RE
authors: Dement'eva
authors: L I
authors: LI
authors: Khisamieva
authors: T L
authors: TL
authors: Zefirov
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000367:Age Factors; D000375:Aging; D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats
chemical_list: D000316:Adrenergic alpha-Agonists; D002316:Cardiotonic Agents; D011743:Pyrimidines; C082246:ICI D2788; D009638:Norepinephrine