| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Division of Endocrinology and Metabolism, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle 98108; and University of Washington, Seattle, Washington 98195
Activation of hepatic nerves increases both hepatic glucose production (HGP) and hepatic arterial vasoconstriction, the latter best described by a decrease of hepatic arterial conductance (HAC). Because activation of canine hepatic nerves releases the neuropeptides galanin and neuropeptide Y (NPY) as well as the classical neurotransmitter norepinephrine (NE), we sought to determine the relative role of these neuropeptides vs. norepinephrine in mediating metabolic and vascular responses of the liver. We studied the effects of local exogenous infusions of galanin and NPY on HGP and HAC to predict the metabolic and vascular function of endogenously released neuropeptide. Galanin (n = 8) or NPY (n = 4) was infused with and without NE directly into the common hepatic artery of halothane-anesthetized dogs, and we measured changes in HGP and HAC. A low dose of exogenous galanin infused directly into the hepatic artery potentiated the HGP response to NE yet had little effect on HGP when infused alone. The same dose of galanin infused into a peripheral vein (n = 8) did not potentiate the HGP response to NE, suggesting that the locally infused galanin acted directly on the liver to modulate NE's metabolic action. In contrast, a large dose of exogenous NPY failed to influence HGP when infused either alone or in combination with NE. Finally, NPY, but not galanin, tended to decrease HAC when infused alone; neither neuropeptide potentiated the HAC response to NE. Therefore, both hepatic neuropeptides may contribute to the action of sympathetic nerves on liver metabolism and blood flow. It is likely that endogenous hepatic galanin acts directly on the liver to selectively modulate norepinephrine's metabolic action, whereas endogenous hepatic NPY acts independently of NE to cause vasoconstriction.
hepatic glucose production; hepatic arterial conductance; neurotransmitter; blood flow
This article has been cited by other articles:
|
|
 |
|
  N. Siebert, D. Cantre, C. Eipel, and B. Vollmar H2S contributes to the hepatic arterial buffer response and mediates vasorelaxation of the hepatic artery via activation of KATP channels Am J Physiol Gastrointest Liver Physiol, December 1, 2008; 295(6): G1266 - G1273. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. G. Hinghofer-Szalkay, N. Goswami, A. Rossler, E. Grasser, and D. Schneditz Reactive hyperemia in the human liver Am J Physiol Gastrointest Liver Physiol, August 1, 2008; 295(2): G332 - G337. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Nishizawa, M. Shiota, M. C. Moore, S. M. Gustavson, D. W. Neal, and A. D. Cherrington Intraportal administration of neuropeptide Y and hepatic glucose metabolism Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1197 - R1204. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Mei, T. O. Mundinger, D. Kung, D. G. Baskin, and G. J. Taborsky Jr. Fos expression in rat celiac ganglion: an index of the activation of postganglionic sympathetic nerves Am J Physiol Endocrinol Metab, October 1, 2001; 281(4): E655 - E664. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
