Restitution of contractility in single ventricular myocytes of guinea pig heart.

摘要: Objective: Our aim was to assess the extent which changes in intracellular Ca2+ stores contribute mechanical restitution heart muscle. Methods: Single, isolated guinea pig ventricular cells were voltage clamped at −45 mV and stimulated continuously 0.5 or 2 Hz with 200 ms depolarizing pulses (35 °C). The recoveries of peak contraction force ( F P) calcium current I Ca) between beats measured contractions interpolated various intervals t d) after a conditioning twitch. Recovery SR load inferred from magnitude C pp) similarly contractures, induced by rapid application 5 mM caffeine. Results: For stimulus rate Hz, both p Ca very small for td recovered along similar time courses t1/2 about 50 ms. Cp maximal as early previous could be measured, 56% maximal. declined throughout interval 50% its value. Similar results obtained increased factor 2. Conclusions: course is coincident recovery inactivation. Caffeine-releasable are fully soon well before complete.