title: [Characteristics of the frequency dependence of the contraction force in the hyperthyroid rat myocardium].
abstract: We have studied the effect of increased contraction frequency (from 0.2 to 1.5 Hz) on developed tension (delta T) in thin papillary muscles of eu- and hyperthyroid rats. The results show that while increasing the contraction frequency, the delta T of euthyroid papillary muscles decreased at lower frequencies than in hyperthyroid group. Also, at the contraction frequencies above 1.0 Hz the absolute and relative levels of delta T of hyperthyroid myocardium were less decreased than in euthyroid preparations. In conclusion, the myocardium of hyperthyroid rat is characterized by a decreased sensitivity to negative inotropic effect of enhanced contraction frequency. In is probably due to the acceleration of the processes of intracellular Ca2+ recycling during diastole under the influence of hyperthyroidism.
authors: E K
authors: EK
authors: Seppet
authors: M A
authors: MA
authors: Eĭmre
authors: L I
authors: LI
authors: Kadaia
authors: A P
authors: AP
authors: Kallikorm
mesh_terms: D000818:Animals; D006339:Heart Rate; D006980:Hyperthyroidism / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine
chemical_list: D013974:Thyroxine
vernacular_title: Osobennosti chastotnoĭ zavisimosti sily sokrashcheniia gipertireoidnogo miokarda krysy.