Reichel H, Baumann K
Recent Adv Stud Cardiac Struct Metab. 1976;11:175-9.
In an isolated perfused left atrium of guinea pig, pressure amplitudes were recorded at 37 degrees C and a stimulation rate of 240/min with interposed variable resting pauses. After prolonged intervals the preparation develops maximum pressure, which does not depend on perfusion time or on any positive inotropic intervention. The latter is found to shorten the time needed for restitution of full contractility. Nifedipine (5 X 10(-7)M) exerts its negative inotropic effect mainly by a delay in restitution time; acetylcholine (2 X 10(-7)M), by a concomitant reduction of all pressure amplitudes over the whole range of stimulus intervals. The latter effect is similar to that of lowering [Ca2+]o.
在豚鼠离体灌注左心房中，于37℃和240次/分钟的刺激频率下记录压力幅度，期间插入不同的静息间歇。经过较长时间后，标本产生最大压力，该压力不依赖于灌注时间或任何正性肌力干预。发现后者可缩短恢复完全收缩性所需的时间。硝苯地平（5×10⁻⁷M）主要通过延迟恢复时间发挥其负性肌力作用；乙酰胆碱（2×10⁻⁷M）则通过在整个刺激间隔范围内同时降低所有压力幅度来发挥作用。后一种效应类似于降低细胞外钙离子浓度的效应。
