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Glucagon modulates superoxide generation in human polymorphonuclear leucocytes
L Al-essa1, M Niwa, M Kobayashi
1Department of Pharmacology, Gifu University School of Medicine, Japan.
Life Sciences
|January 1, 1993
Summary
Glucagon enhances bacterial infection responses in white blood cells (leukocytes) by increasing a key signaling molecule. Tyrosine kinase inhibition reveals a complex interaction affecting superoxide production.
Area of Science:
- Immunology
- Cellular Signaling
- Biochemistry
Background:
- Leukocytes (white blood cells) have receptors for glucagon.
- Glucagon levels rise during bacterial infections.
- The precise role of glucagon in leukocyte function during infection is unclear.
Purpose of the Study:
- To investigate the effect of glucagon on superoxide generation in polymorphonuclear neutrophils (PMNs).
- To examine the role of second messengers in glucagon-mediated PMN responses.
- To understand the interplay between glucagon, tyrosine kinase, and PMN activation.
Main Methods:
- Assessed glucagon's effect on PMN chemiluminescence (superoxide generation).
- Investigated glucagon's impact on inositol trisphosphate (IP3) and cyclic AMP (cAMP) levels.
- Utilized ST-638, a tyrosine kinase inhibitor, to probe signaling pathways.
Main Results:
- Glucagon alone did not induce chemiluminescence but enhanced FMLP-induced, not PMA-induced, chemiluminescence.
- Glucagon increased intracellular IP3 and cAMP levels in PMNs.
- ST-638 reversed glucagon's enhancement to inhibition and attenuated IP3 increases.
Conclusions:
- Glucagon enhances FMLP-stimulated superoxide generation in PMNs primarily by elevating IP3.
- Tyrosine kinase inhibition unmasks an inhibitory effect of increased cAMP on superoxide production.
- Glucagon modulates PMN function through complex signaling pathways involving IP3 and cAMP.