[Effects of hyperosmolarity and furosemide on resting membrane potentials and skeletal muscle fiber volume in rats].

The changes of the muscle fibres volume and resting membrane potential (RMP) were studied following treatment with hypertonic medium and furosemide. The volume changes in hypertonic medium began with cell shrinkage and later have been followed by the volume increase up to normal level during 30-40 minutes. At the same time the medium hypertonicity caused muscle fibres depolarisation. The hypertonic-induced decrease of the RMP was delayed in the furosemide-treated muscle. Besides, furosemide abolished the muscle fibres volume restorative properties in hypertonic medium. It is suggested that the membrane depolarisation and cell volume restoration in hypertonic medium are the resultant effects of intracellular chloride ions level elevation which, in turn, have been evoked by activation of furosemide-sensitive Cl(-)-influx system.