Stimulation of the Na+ pump by hypotonic solutions in skeletal muscle.
The fractional loss of 22 Na+ from frog sartorius muscle is increased when the tonicity of the external solution is reduced. The effect, which is larger the lower the osmolarity, exhibits the following characteristics: (1) quick onset and reversibility, (2) is not reduced in the absence of external Na+, (3) is completely abolished by strophanthidin (3. 10-5 M), (4) is neither the result of membrane depolarization nor K+ accumulation in the extracellular space.
D000818:Animals; D001001:Anura; D007038:Hypotonic Solutions / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013327:Strophanthidin / Q000494:pharmacology
D007038:Hypotonic Solutions; D013327:Strophanthidin; D012964:Sodium; D011188:Potassium