Zinc-induced alterations in contractile properties of rat diaphragm muscle in vitro

Golgeli A. , Dursun N. , Suer C. , Özesmi Ç. , Aydogan S.

BIOLOGICAL TRACE ELEMENT RESEARCH, cilt.60, ss.251-260, 1997 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 60 Konu: 3
  • Basım Tarihi: 1997
  • Doi Numarası: 10.1007/bf02784445
  • Sayfa Sayıları: ss.251-260


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.