Interaction between the sarcoplasmic reticulum and mitochondria in the control of contractile calcium in guinea-pig atria--does it exist?
The inhibitory action of caffeine on calcium (Ca2+) release from the sarcoplasmic reticulum (SR) and interference with mitochondrial (Ca2+) fluxes by a mitochondrial uncoupler protonfore CCCP were utilized to define a calcium pool responsible for potentiation of post-rest twitch tension in guinea-pig atria. The Ca2+ fluxes were assessed by means of 45Ca2+. Caffeine and CCCP when applied separately did not affect post-rat 45Ca2+ content. Yet, when they were applied together it was markedly reduced to the resting level. It is concluded that a possible source of contractile Ca2+ may be located in mitochondria and an eventual shift of Ca2+ between mitochondria and the SR seems to be a plausible assumption.
Prokopczuk
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Department of Clinical Physiology, Medical Centre of Postgraduate Education, Warsaw.
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria; D007425:Intracellular Membranes / Q000378:metabolism; D008297:Male; D008929:Mitochondria, Heart / Q000502:physiology*; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000502:physiology*
D002110:Caffeine; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D002118:Calcium