Gölgeli A, Dursun N, Süer C, Ozesmi C, Aydogan S
Department of Physiology, Faculty of Medicine, University of Erciyes, Kayseri, Turkey.
Biol Trace Elem Res. 1997 Dec;60(3):251-60. doi: 10.1007/BF02784445.
The effect of zinc ions on the isometric contraction of rat diaphragm muscles in the presence and in the absence of external calcium was studied. Using a transducer, the isometric force was measured as a function of supramaximal electrical stimulation, either directly or indirectly applied to the muscle. The following parameters were measured: peak twitch tension, PT, twitch contraction time, CT, relaxation half-time, RT-1/2, and peak rates of tension increase and decrease, +dP/dt and -dP/dt. The following zinc-induced alterations were observed: an increase of the PT; a decrease of the RT-1/2; an increase in the +dP/dt and -dP/dt. The CT was not changed significantly. Our results suggest that zinc ions have a positive inotropic effect on isolated diaphragm muscle. The increase in PT may be explained by a zinc-activated Ca2+ uptake by sarcoplasmic reticulum. This was followed by an increase in the rate of rise of tension development, which was secondary to increased -dP/dt. The mechanism(s) by which extracellular Ca2+ contributes to this action of zinc is not known.
研究了锌离子在有和无细胞外钙存在的情况下对大鼠膈肌等长收缩的影响。使用传感器，直接或间接对肌肉施加超强电刺激，测量等长力随刺激的变化。测量了以下参数：单收缩峰值张力（PT）、单收缩收缩时间（CT）、舒张半衰期（RT-1/2）以及张力增加和降低的峰值速率（+dP/dt和-dP/dt）。观察到锌诱导的以下变化：PT增加；RT-1/2降低；+dP/dt和-dP/dt增加。CT无显著变化。我们的结果表明，锌离子对离体膈肌有正性肌力作用。PT的增加可能是由于锌激活肌浆网摄取Ca2+所致。随后张力发展速率增加，这是-dP/dt增加的继发结果。细胞外Ca2+促成锌这种作用的机制尚不清楚。
