Cyclic AMP and Early Contractile Failure
Cyclic AMP was measured in the isolated rat heart during anoxia in an attempt to demonstrate if this nucleotide is in any way related to the extent and rate of contractile failure. Isolated rat hearts were subjected to 15 min of normoxia followed by periods of between 1 and 300 sec of anoxia. Contractile force and its failure were monitored throughout. Tissue samples were obtained at various times using high-speed freeze-clamping techniques, and the frozen samples were taken for extraction and cAMP analysis. The results showed a significant increase in the levels of cAMP during the first 5 sec of anoxia, followed by a return to control levels as contractile activity fell to 40% of control. A second and significant increase in cAMP occurred during the following 60 sec. These results indicate major changes in cAMP levels during the first minute of anoxia-induced contractile failure and suggest that increases in this nucleotide may be related to extent and rate of contractile failure.
KeywordsContractile Activity Contractile Force cAMP Content Failure Curve Endogenous Norepinephrine
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- 1.Albert, N. R., and Gordon, M. A. 1962. Myofibrillar adenosine triphosphatase activity in congestive heart failure. Am. J. Physiol, 202:940–946.Google Scholar
- 5.Brown, B. L., Albano, J. D. M., Ekins, R. P., and Scherzi, A. M. 1976. A simple and sensitive saturation assay method for the measurement of adenosine 3′,5′-cyclic monophosphate. Biochem. J. 121:561–562.Google Scholar
- 6.Coraboeuf, E., Derouboix, E., and Hoerter, J. 1976. Control of ionic permeabilities in normal and ischemic heart. Circ. Res. 38(Suppl. l):92–98.Google Scholar
- 7.Danforth, W. H. 1965. Activation of glycolytic pathway in muscle. In: B. Chance, R. W. Eastabrook, and J. R. Williamson (eds.), Control of Energy Metabolism, pp. 287–297. Academic Press, New York.Google Scholar
- 19.Nakamura, Y., and Schwartz, A. 1972. The influence of hydrogen ion concentration on calcium binding and release by skeletal muscle sarcoplasmic reticulum. J. Gen. Physiol. Google Scholar
- 21.Opie, L. H. 1976. Effects of regional ischemia on metabolism of glucose and fatty acids. Circulation38(Suppl. l):52–68.Google Scholar
- 24.Poole-Wilson, P. A., Lakatta, E. G., and Nayler, W. G. 1977. The effects of acidosis on myocardial function and the uptake of calcium during and after hypoxia. Clin. Sci. Mol. Med. 52:2–3.Google Scholar
- 25.Poole-Wilson, P. A., and Langer, G. A. 1976. The effect of acidosis and manganese on calcium exchange in the myocardium of the rabbit. J. Physiol. (Lond.)265:20–21.Google Scholar
- 28.Verma, S. C, and McNeil, J. H. 1976. Actions and interactions of theophylline and imidazole on cardiac contractility, Phosphorylase activation and cyclic AMP. Arch. Int. Pharmacol. 221:4.Google Scholar
- 29.Williamson, J. R., Schaffer, S. W., Ford, A., and Safer, B. 1976. The cellular basis of ischemia and infarction, contribution of tissue acidosis to ischemic injury in the perfused rat heart. Circulation53(Suppl. 1):3–14.Google Scholar