The effect of fluoride and calcium ions upon the insulin plus lactate-stimulated K uptake and respiratory rate of frog muscles
✍ Scribed by K. E. O'Niell; J. F. Manery; E. E. Dryden
- Publisher
- John Wiley and Sons
- Year
- 1966
- Tongue
- English
- Weight
- 836 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Using paired frog muscles it was shown that fluoride caused no observable change in the rate of oxygen consumption in Ca++-free Ringer's solution, but stimulated the rate in Ca+ +-containing Ringer's; the obvious explanation for this stimulation is the spontaneous activity of the muscle caused by the rapid lowering of Ca+ + ion concentration when fluoride was added. Fluoride had no effect on potassium movement in these experiments. In a Ca++-free solution fluoride (0.03 M ) inhibited the insulin + lactate-stimulated oxygen consumption of muscles which had been adapted to the absence of calcium by overnight soaking. In Ca+ +-containing Ringer's there was no net effect of fluoride, demonstrating the fact that the direct inhibition of oxygen consumption was cancelled by the indirect stimulation caused by the fluoride-lowering of the Ca+ + ion concentration. Fluoride depressed the IL-induced K uptake but for this effect some calcium, albeit a very low concentration, was necessary. Fluoride did not alter the muscle glycogen concentrations.
The only observable effect of calcium (in the absence of fluoride) was a rise in respiration caused by exposure to a sudden reduction in Ca+ + ion concentration. Both the &stimulated 0 2 rate and K uptake were independent of Ca++ ions since they occurred in Ca++-free adapted muscles, in muscles exposed to a rapid reduction of Ca++ ions as well as in muscles in a Ca++-containing Ringer's solution.