This paper is only available as a PDF. To read, Please Download here.
This study was initiated to determine whether glycogen phosphorylase activation was defective in hearts of alloxan diabetic rats. When hearts were perfused by gravity flow for 1 to 10 min with various concentrations of epinephrine, activation of glycogen phosphorylase in the diabetic was significantly greater at every time and epinephrine concentration than that seen in the normal. Cyclic AMP accumulation and protein kinase activation by epinephrine in the diabetic were not appreciably different or were lower than the normal responses to the hormone. The effects of epinephrine on cAMP and protein kinase were blocked in both normal and diabetic hearts by propranolol. While the beta blocker prevented phosphorylase activation in the normal hearts, it did not block phosphorylase activation by epinephrine in the diabetic hearts. Likewise, the alpha agonist phenylephrine activated phosphorylase in the diabetic but not in the normal hearts. While glucagon produced the same phosphorylase hypersensitivity in diabetic hearts, the cAMP and protein kinase responses were not altered by diabetes. Phosphorylase phosphatase activity was found to be unaltered by either epinephrine or diabetes, whereas phosphorylase kinase activation by epinephrine in the diabetic was double the normal response. These data are consistent with a diabetes-related unmasking of an alpha effect on cardiac phosphorylase activation and an unexplained increase in the sensitivity of phosphorylase kinase activation by protein kinase.
REFERENCES
- Circ. Res. 1979; 44: 145-153
- Mol. Pharmacol. 1965; 1: 168-177
- J. Biol. Chem. 1966; 241: 5893-5898
- J. Biol. Chem. 1966; 241: 5899-5903
- Mol. Pharmacol. 1968; 4: 61-69
- Mol. Pharmacol. 1968; 4: 522-530
- J. Biol. Chem. 1975; 250: 4832-4840
- J. Biol. Chem. 1977; 252: 910-918
- Life Sci. 1980; 25: 2075-2078
- Am. J. Physiol. 1967; 212: 815-822
- J. Biol. Chem. 1963; 238: 1592-1597
- Am. J. Physiol. 1979; 236: H808-H812
- Bergmeyer H.U. Methods of Enzymatic Analysis. 4. Academic Press, New York1974: 2101-2110
- Bergmeyer H.U. Methods of Enzymatic Analysis. 3. Academic Press, New York1974: 1238-1242
- Proc. Natl. Acad. Sci. U. S. A. 1970; 67: 305-312
- J. Biol. Chem. 1978; 253: 5389-5394
- Anal. Biochem. 1968; 25: 486-499
- Anal. Biochem. 1972; 47: 20-27
- Methods Enzymol. 1974; 38: 287-290
- J. Biol. Chem. 1979; 254: 7345-7352
- Proc. Natl. Acad. Sci. U. S. A. 1979; 76: 1570-1574
- Annu. Rev. Physiol. 1974; 36: 413-459
- Mol. Pharmacol. 1977; 13: 965-975
- J. Biol. Chem. 1976; 251: 6724-6729
- J. Biol. Chem. 1965; 240: 2778-2785
- J. Pharmacol. Exp. Ther. 1980; 212: 253-258
- J. Pharmacol. Exp. Ther. 1968; 159: 82-90
- Can. J. Physiol. Pharmacol. 1971; 49: 508-512
- Jap. J. Pharmacol. 1973; 23: 373-379
- Naunyn-Schmiedebergs Arch. Pharmacol. 1975; 287: 61-72
- Acta Pharmacol. Toxicol. 1976; 39: 232-240
- Fed. Proc. 1979; 38: 1027
- Fed. Proc. 1979; 38: 270
- Am. J. Physiol. 1981; (in press)
- Diabetes Care. 1980; 3: 526-529
Article Info
Publication History
Published online: February 25, 1981
Identification
Copyright
© 1981 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.
User License
Creative Commons Attribution (CC BY 4.0) | How you can reuse
Elsevier's open access license policy
Creative Commons Attribution (CC BY 4.0)
Permitted
- Read, print & download
- Redistribute or republish the final article
- Text & data mine
- Translate the article
- Reuse portions or extracts from the article in other works
- Sell or re-use for commercial purposes
Elsevier's open access license policy





