CAT HEART MUSCLE IN VITRO. VII. THE TEMPERATURE DEPENDENCE OF STEADY STATE K EXCHANGE IN PRESENCE AND ABSENCE OF NACL.
In quiescent cat papillary muscles J(K), the rate of exchange of cellular K with K(42) in the steady state, has been measured in the presence and absence of NaCl over a wide range of temperatures. J(K) was found to be independent of the presence of external NaCl under the steady state conditions investigated. The Arrhenius plot for K exchange was linear over a range of temperatures from 2.5 to 37.5 degrees C in the absence of NaCl, and from 17.5 to 37.5 degrees C in the presence of NaCl. The corresponding apparent activation energies were, respectively, 10,200 and 8,800 calories/mole. J(K) in the absence of NaCl was not affected by 10(-5)M ouabain. These results are consistent with a passive distribution for the K of heart muscle cells. The observations suggest that a carrier-mediated forced exchange of K for Na does not occur during the steady state in mammalian heart muscle.
D000818:Animals; D002415:Cats; D066298:In Vitro Techniques; D007477:Ions; D008660:Metabolism; D010042:Ouabain; D010210:Papillary Muscles; D010600:Pharmacology; D011188:Potassium; D011194:Potassium Isotopes; D012106:Research; D012964:Sodium; D012965:Sodium Chloride; D013395:Sucrose; D013696:Temperature
D007477:Ions; D011194:Potassium Isotopes; D012965:Sodium Chloride; D013395:Sucrose; D010042:Ouabain; D012964:Sodium; D011188:Potassium
CATS; EXPERIMENTAL LAB STUDY; METABOLISM; OUABAIN; PAPILLARY MUSCLES; PHARMACOLOGY; POTASSIUM; POTASSIUM ISOTOPES; SODIUM CHLORIDE; SUCROSE; TEMPERATURE