[Effect of brief papillary muscle stretch on 2 contraction components in the presence of noradrenaline in guinea pigs].
In isolated guinea-pig papillary muscles perfused with Tyrode's solution, quick stretching did not affect the isotonic contraction when applied at its fast shortening phase, and accelerated the relaxation if the stretching coincided with the later phases of the contractile response. In presence of noradrenaline the contraction revealed two components. The amplitude of the 1st component was augmented whereas its time to peak did not change when the stimulation frequency had been increased. The amplitude of the 2nd component and its time to peak both diminished at the increase of the stimulation frequency. The changes of time to peak were always closely related to the changes of the AP duration. The 1st contraction component seems to be calcium release from sarcoplasmatic reticulum whereas the 2nd component is determined by the AP duration.
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology; D006168:Guinea Pigs; D009200:Myocardial Contraction / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D010210:Papillary Muscles / Q000187:drug effects*; D010812:Physical Stimulation; D012519:Sarcoplasmic Reticulum / Q000502:physiology; D013997:Time Factors
D002118:Calcium; D009638:Norepinephrine
Vliianie kratkovremennogo rastiazheniia papilliarnoĭ myshtsy morskoĭ svinki na dve komponenty sokrashcheniia v prisutstvii noradrenalina.