The effects of repeated exposure to anoxia on intracellular calcium,glycogen and lactate in isolated ferret heart muscle |
| |
Authors: | John A. Lee David G. Allen |
| |
Affiliation: | (1) Department of Physiology, University College London, Gower Street, WC1E 6BT London, UK |
| |
Abstract: | Isolated cardiac tissue from the ferret was repeatedly exposed to anoxia while perfused with glucose-containing Tyrode solution. In one series of experiments, papillary muscles were injected with aequorin to measure intracellular Ca2+. On the first exposure to anoxia, the Ca2+ transients often increased, but on subsequent exposures this increase disappeared and eventually the Ca2+ transients declined on exposure to anoxia. This decline in the Ca2+ transients could be converted back to an increase by a 1 h exposure to an elevated (×5) glucose concentration. Exposure of aerobic muscles to 10 mM lactic acid caused a similar increase in the Ca2+ transients to that seen in early exposures to anoxia. In a second series of experiments, performed on Langendorff-perfused hearts, measurements were made of glycogen concentration preceding, and lactate production during, exposures to anoxia. At a constant level of glucose, glycogen concentration and lactate production were found to decline on repeated exposures to anoxia, and both were increased after a period of elevated glucose and reduced stimulation frequency. These results suggest that the response of the Ca2+ transients to anoxia is dependent on the metabolic status of the muscle. The increase in the Ca2+ transients during an early eposure to anoxia may be a consequence of lactic acid production due to accelerated glycolysis. Repeated exposures to anoxia reduce glycogen concentration and lactate production and this reduces the rise in the Ca2+ transients. |
| |
Keywords: | Aequorin Anoxia Intracellular calcium Glycolysis Heart Ventricular muscle |
本文献已被 SpringerLink 等数据库收录! |
|