caa a22 4500 475744691 CHVBK 20180406123509.0 cr unu---uuuuu 170329e20000101xx s 000 0 eng 10.1023/A:1005618720122 doi (NATIONALLICENCE)springer-10.1023/A:1005618720122 Loop diuretics inhibit detubulation and vacuolation in amphibian muscle fibres exposed to osmotic shock [Elektronische Daten] [Kamron Khan, Jeremy Skepper, Austin Hockaday, Anthony Burgess, Christopher Huang] The effect of loop diuretics at concentrations known to influence cellular water entry coupled to Na-K-Cl co-transport, upon the vacuolation and detubulation following osmotic shock, was investigated in amphibian skeletal muscles. These were exposed to a glycerol-Ringer solution (18 min), an isotonic Ca2+/Mg2+ Ringer solution and cooling. Adding bumetanide (1.0 and 2.0 μM) to these solutions sharply reduced the incidence of detubulation, assessed by abolition or otherwise of action potential after-depolarisations, from 93.9 ± 4.7% (n = 6) to 5.0 ± 1.1% (n = 4: mean ± SEM: 2.0 μM bumetanide). It dramatically reduced the number and fraction of muscle volume occupied by tubular vacuoles, measured using confocal microscopy, from 60.3 ± 4.3% (n = 10) to 9.0 ± 1.1% (n = 35). The incidence of large horseradish peroxidase-lined tubular vacuoles, viewed using electronmicroscopy, similarly was reduced with 2 μM bumetanide in the glycerol-Ringer solution. Bumetanide acted through cellular volume adjustments early in the detubulation protocol. Thus, it exerted its maximum effect when added to the glycerol-Ringer, rather than the Ca2+/Mg2+ Ringer solution. Furthermore, whereas fibre diameters measured using scanning electron microscopy returned to normal during glycerol treatment relative to those of control fibres left in isotonic Ringer, addition of 2.0 μM bumetanide in the glycerol Ringer left markedly smaller fibre diameters. Finally equipotent concentrations of the chemically distinct loop diuretics, furosemide and ethacrynic acid similarly influenced detubulation. These findings implicate Na-K-Cl co-transport in the water entry into muscle fibres that would be expected following introduction of extracellular glycerol. This might then enable the subsequent Na-K-ATPase dependent water extrusion that produces the tubular distension (vacuolation) and detachment (detubulation) following glycerol withdrawal, phenomena also observed in muscular dystrophy. Kluwer Academic Publishers, 2000 Khan Kamron Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut Skepper Jeremy Multi-Imaging Centre, Department of Anatomy, University of Cambridge, Cambridge, UK aut Hockaday Austin Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut Burgess Anthony Multi-Imaging Centre, Department of Anatomy, University of Cambridge, Cambridge, UK aut Huang Christopher Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/1(2000-01-01), 79-90 0142-4319 21:1<79 2000 21 10974 https://doi.org/10.1023/A:1005618720122 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005618720122 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Khan Kamron Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut NATIONALLICENCE 700 1- Skepper Jeremy Multi-Imaging Centre, Department of Anatomy, University of Cambridge, Cambridge, UK aut NATIONALLICENCE 700 1- Hockaday Austin Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut NATIONALLICENCE 700 1- Burgess Anthony Multi-Imaging Centre, Department of Anatomy, University of Cambridge, Cambridge, UK aut NATIONALLICENCE 700 1- Huang Christopher Physiological Laboratory, Downing Street, CB2 3EG, Cambridge, UK aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/1(2000-01-01), 79-90 0142-4319 21:1<79 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer