Effect of calcium on the potassium content of striated muscle

✍ Scribed by Torda, Clara

• Publisher: Wiley (John Wiley & Sons)
• Year: 1941
• Tongue: English
• Weight: 624 KB
• Volume: 18
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030180214

✦ Synopsis

T W O FIGURES

Thc well-known antagonism of calcium and potassium salts and certain aspects of the actions of these ions as chemical stimulants and depressants of the neuromuscular system suggested the investigation of the effect of varying the concentration of Ca++ on the potassium content of striated muscles.

METHOD

The muscles studied were the gastrocnemius, se~iiimerribranosus, biceps femoris and sartorius of the frog. The K content of about 950 muscles was determined.

The intact muscles were shaken for periods of from 1 to 6 hours in various isotonic solutions. The solutions employed were : (1) Ringer ' S solution (115 mhl NaC1, 2.0 mR1 KCl, 1.8 mM CaCl,, and 2.3 m'RI NaHCO,), (2) a Ca++-free modified Ringer's solution, ( 3 ) modified Ringer's solution containing from 0.18 to 27.0 m l l CaCl,, (4) Rf-free modified Ringer's solution, (5) modified Ringer's solution coiitainiiig from 4 to 20 nihf KCI, (6) isotonic sodium citrate solution contaiiiiiig 0.0 or 2.0 OT 10.0 mhf KCl, and (7) isotonic sodium oxalate solution containing 0.0, 2.0 or 10.0 mM KCl. In order to maintain isotonicity, changes in the Kf or Ca+ concentration were compensated for by an equivalent increase or decrease in the amount of Naf. Usually three muscles of the same kind were shaken together in 250 cc. of the solution. The experiments were conducted at room temperature (18-22°C.) and at pH 7.8. During the period of shaking, air was bubbled through the solution. After shaking, the muscles were dried to constant weight at 110°C. and the K values were determined and expressed in terms of milliequivalents per 100 gni. of dried tissue. Dry weight was used to