Effects of Anoxia on Intracellular Free Ca2+ in Isolated Cardiomyocytes From Turtles
| Autor: | Norbert Heisler, Jeremy S Wasser |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Male
medicine.medical_specialty chemistry.chemical_element In Vitro Techniques Calcium Calcium in biology Internal medicine medicine Extracellular Animals Myocyte Hypoxia Fluorescent Dyes Acidosis biology Myocardium General Medicine Hydrogen-Ion Concentration biology.organism_classification Turtles Endocrinology Microscopy Fluorescence chemistry Biochemistry medicine.symptom Fura-2 Painted turtle Perfusion Intracellular |
| Zdroj: | Comparative Biochemistry and Physiology Part A: Physiology. 116:305-312 |
| ISSN: | 0300-9629 |
| Popis: | One of the most important negative consequences of hypoxic stress in the mammalian myocardium is a breakdown in intracellular calcium homeostasis. This study examines the effects of anoxic stress on intracellular calcium regulation in isolated ventricular myocytes from a hypoxia tolerant vertebrate, the western painted turtle (Chrysemys picta bellii). Isolated calcium tolerant cardiomyocytes from turtle hearts were mounted on a glass cover slip that formed the bottom of a sealed, Plexiglas perfusion chamber. Free [Ca2+]i (determined by FURA2 fluorescence) in isolated turtle cardiomyocytes averaged 31.7 +/- 3.2 nM after 30 min of normoxic perfusion (20 degrees C, pHc = 7.77). This value is on the low end of the published range for mammalian cardiomyocytes. Perfusion with anoxic Ringer equilibrated with 3% CO2, resulted in a significant increase in free [Ca2+]i to 941 +/- 494.6 nM after 60 min. Increasing the CO2 in the perfusion solution to 5% or 6% blunted this rise (peak levels after 60 min of anoxia were 420.5 +/- 176.0 nM and 393.8 +/- 132.8 nM, respectively). A further increase to 8% CO2 increased the maximal value for free [Ca2+]i to 610.9 +/- 297.5 nM. In eight cells from the 5% CO2 protocol in which [Ca2+]i was monitored during recovery, reperfusion with normoxic Ringer rapidly lowered intracellular calcium to 92.8 +/- 9.7 nM within 15 min. Anoxia at relatively high extracellular (and hence intracellular) pH results in an increase in free [Ca2+]i comparable in magnitude and time course to that seen in some mammalian cardiomyocyte preparations. Perfusion of anoxic myocytes with Ringer equilibrated with either 5% or 6% CO2 blunted this increase in intracellular calcium, possibly an example of the pH paradox effect. A more severe combination of respiratory acidosis and anoxia (8% CO2) removed this protective effect. |
| Databáze: | OpenAIRE |
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