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Calcium paradox in guinea-pig ventricular myocytes
M S Suleiman1, J J Edmond, G K Bulstrode
1University Department of Cardiac Surgery, Bristol Royal Infirmary, UK. M.S.Suleiman@bristol.ac.uk
Abstract:
Measurement of the release of lactate dehydrogenase (LDH), the development of contracture and the exclusion of the dye Trypan Blue were made in isolated guinea-pig ventricular myocytes subjected to conditions that evoke a calcium paradox in intact heart. Incubation at 25 degrees C reduced the release of LDH associated with mechanical manipulation of the myocytes so that during prolonged incubation in media free of Ca2+ and Mg2+ ions at 25 degrees C little release of LDH occurred. A significant release of LDH into the incubation media was provoked on repletion of the divalent cations. This release was accompanied by a marked decrease in the percentage of rod-shaped myocytes and their ability to exclude Trypan Blue. The results provide evidence for the existence of the calcium paradox in isolated guinea-pig ventricular myocytes as originally defined.