Effects of thapsigargin on stimulation frequency--dependent changes in mitochondrial calcium in rat cardiac myocytes.
We investigated in the single myocytes of rat heart the effect of blocking of ATP-ase of sarcoplasmic reticulum (SR) on mitochondrial Ca2+ uptake and release. Mitochondrial Ca2+ content was investigated as Mn(2+) - resistant fluorescence of Indo 1 - AM loaded into cells. SR ATP-ase was blocked with 10(-6) M thapsigargin (Tg). Tg blocked almost completely stimulation -dependent mitochondrial Ca2+ uptake and slowed down its release despite that the maximal cytosolic Ca2+ concentration was not decreased. We propose that mitochondrial stimulation -dependent Ca2+ uptake is greatly enhanced by [Ca2+] built by SR in microdomains adjacent to these organelle.
Lewartowski
B Pytkowski B
BP
Department of Clinical Physiology, Medical Center of Postgraduate Education, Marymoncka 99, 01-813, Warsaw, Poland. bohdanp@cmkp.edu.pl
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes; D007211:Indoles; D008297:Male; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000201:enzymology; D019284:Thapsigargin / Q000494:pharmacology*
D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007211:Indoles; D012430:Ruthenium Red; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; C048960:indo-1