title: Effect of isoniazid on the protoplasmic viscosity in Mycobacterium tuberculosis.
abstract: The effect of isoniazid on the protoplasmic viscosity in the H37Ra strain of Mycobacterium tuberculosis was determined by using electron spin resonance spectroscopy and a small spin label tempone (2,2,6,6-tetramethylpiperidone-N-oxyl radical). Isoniazid (0.5 mug/ml) caused the internal cellular viscosity to increase gradually over the first 15 h of exposure from a rotational correlation time value (T(c)) of 2.4 x 10(-10) to 3.4 x 10(10) s and then decrease linearly to the control level after 27 h. These results could be interpreted to mean that isoniazid allows a continued and normal synthesis of the protoplasmic components while the rate of increase in the cell volume is reduced. A degradative process may begin after the initial 15-h exposure time, which would cause the reduction in the internal viscosity.
mesh_terms: D003593:Cytoplasm / Q000187:drug effects*; D007538:Isoniazid / Q000494:pharmacology*; D009169:Mycobacterium tuberculosis / Q000166:cytology* / Q000187:drug effects; D014783:Viscosity
chemical_list: D007538:Isoniazid